I will preface this by saying that I got EXTREMELY lucky on Tuesday 14th of November when I did this challenge. But having said that, my plan, if executed perfectly, should have a potential to just achieve a sub-17 hour time.
This obviously still falls massively short of the old record of 15:45:38 set by Andi and James for the 270 station configuration, which says to me that a sub 16 hour time is definitely possible in the 272 station configuration and that my route could definitely be improved upon. I however have found it extremely difficult to improve upon the sub-17hr route which I eventually settled on for this third attempt due to the limitation of a Heathrow Start and morning Olympias. Maybe you can help me with some suggestions to improve my route?

From my base in West London, the N9 sets up a convenient connection to the start line at Hounslow West. Piccadilly 220 arrived on time at Heathrow T4 and also departed just about on time at 5:02:55am. As I pulled into T2&3 4.5 mins later I spotted the westbound train on the platform with its doors open. This T5 train has almost always departed early on every single one of my attempts, and so I hoped it would remain on the platform long enough, but knowing I would have the 5:14am HX as a fall back should I need it.
Luckily, the beeps of the doors started to sound as I hopped onto the train, perfect connection to start the day, one of many as I was about to find out.
We arrived at T5 on time/early at 5:11am. Train 222 today was operated by a driver who really wanted to reach the depot, and as such, we left T5 a full minute early at 5:21am, and remained ahead of the timetable until Northfields, where the inevitable hold on the platform dragged us back onto timetabled departure time. Luckily, this was not a factor for our District line connection at Hammersmith, where the 064 District line bound for Upminster was waiting. A second perfect connection. We were doing very well.
Having tapped out at West Kensington a full District line train ahead at 6:00am (the Barking train is timetabled for 6:02am), it was nice to not have to fully sprint the 0.7 miles to Olympia. 7 minute connection on foot later (the 28 bus unfortunately had just departed a minute before my arrival at WK), we saw the 064 train stood on Platform 1 at Olympia. The train left as scheduled at 6:10:30am, and we were on the platform at Earl's Court by 6:14am. Here is the first place where I deviated from my previous route, and instead of doing Edgware Road/Paddington loop now, I decided to tackle the rest of the Piccadilly line. Down into the bowels of Earl's Court and we reached the platform just as Piccadilly 353 arrived to take us to Cockfosters. 3/4 perfect connections so far, we were off to a good start.
A long long ride to Cockfosters later, I was in time to catch the 7:10 384 to High Barnet. Unfortunately, for one reason or another, this bus was cancelled (seemingly due to a bus not having come down from Edgware). Not a big deal, we used the 299 down to Cockfosters road to connect to a 307 that was just coming down the hill. Due to the early arrival here, we avoided the bulk of the school traffic and we were on a train leaving High Barnet at 7:31.
Unfortunately, this 5 mins set back did push us a train back on the MHE branch. Wanting to be a hero and catch the train from MHE, I got out at West Finchley and ran for the 221, hoping I would catch the 7:47 Kennington train, forgetting that now the school traffic would pick up. No damage done though, and a 13 min transfer between WF & MHE meant that I was early for the 8:00 Morden service. Train 026 took us down to Moorgate, where we picked up the Met line to Baker Street. (Another perfect transfer here, we were racking them up nicely).
Jubilee 302 arrived into the platform as I ran down the escalators at Baker Street, and took us up to Stanmore in good time. No 142 bus meant a
3 min wait for a double back to Canons Park was the best option. A 1 min bus wait and a total 7 min Canons Park - Edgware Connection later meant that all 4 northern Sections were completed before 10am, we were doing well.
It is worth noting here that there was a noticeable 10 minute service gap at Edgware at this time, and because there was no CX service on the Edgware Branch at the time, I needed to change at Camden Town, not much time lost though, and soon enough we were at Goodge Street. Once again though, we had a problem. There was no double back to Warren Street, and the dot matrix indicators on the NB platform were broken (and have been broken a long time), so it was a nervous wait for a train. Thankfully it only ended up being 3 mins or so.
A quick run through Warren Street later and we were onto a Victoria line service. I settled in for the ride to Walthamstow, only to hear "this is a Victoria line train to Seven Sisters" *sigh*
Quick change at Finsbury Park later, we reached Walthamstow at 10:26. As we would probably miss the 10:28am Overground at Queen's Road, I opted for the bus option to connect to the Central line. Use of the 69 and W16 busses later, we found ourselves at Leytonstone after 21 minutes. Not a horrifically long change, nor anything to ride home about.
At Leytonstone the decision was made for us, as there was no Epping train for another 10 mins, Hainault was the best choice. Around a 5 minute change at Hainault onto train 173, we were back onto theoretical best pace. We arrived into Woodford right on time at 11:17am. Unfortunately, the Epping bound service passed as by as we passed Woodford Junction, meaning that I was doomed to wait another 10 mins for another Epping train due to another gap in the service. Not a massive deal, but this would start the spiral that would impact us later in the day.
Due to the gap in the service, the 026 Central line which took us up to Epping from Woodford also took us all the way back to West Ruislip after a full 1hr 30min ride. The heavy rain had flooded the High Road between Ickenham and West Ruislip, meaning the bus option was gone. Not a big deal, a 7 min connection on foot later put us on for a perfect connection at Ickenham for a connection down to Uxbridge. Another perfect double back at Uxbridge brought us to West Harrow at 1:49pm. The 1:57pm Piccadilly line from Rayners Lane was around 10 minutes late though, and this put us back once again until North Ealing.
North Ealing to West Acton was done in 4 mins, meaning I just caught Central 105 into Ealing Broadway, perfect connection number 8 brought us back to 15 mins behind theoretical perfect. This coupled with the perfect connection onto the 2:28pm District Line train bought us another 5 mins. Perfect connection 10 at Turnham Green down to Richmond coupled with perfect connection 11 as the double back at 2:53pm meant we were still within reach of theoretical perfect. However this is when the wheels started to come off.
At Stamford Brook we were held for an unusual length of time "due to a trespasser further down the track". As we pulled into Ravenscourt Park, we were told that "track current was now turned off due to a trespasser between High Street Kensington and Earl's Court". It was bound to happen, but this was a devastating setback. Quick connection to a bus got us to Hammersmith H&C in 7 mins, but now we were 20 mins behind. Furthermore, at this point the circle line was suspended when we most needed it. (Even though clockwise services from Hammersmith seemed to be running fine).
As we pulled into Edgware Road, I saw the crowds of people on Platforms 2 & 3 and the dot matrix showing 10+ min wait times meant I needed to improvise. I decided to pick up southbound Bakerloo at Baker Street instead. Perfect connection 12 for the Bakerloo 245. Transfer to Northern to London Bridge and then to Southwark on the Jubilee. The double back took a full 5 mins at Southwark but it didn't matter due to c2c service patterns at West Ham. The 16:38 Shoeburyness c2c dropped us at Upminster nicely for the 4:55pm District line back. A long ride to Aldgate East later left us with a transfer to Aldgate. I was hoping for a good transfer at Aldgate, but this wasn't to be, the circle line I needed was running 11 mins late, and left us with an 8 minute wait. No perfect transfer here

We took the circle line to Sloane Square, perfect double back (number 14) and perfect Victoria line at Victoria. A mediocre 10 min connection between Vauxhall and BPS left us at Battersea Power Station at 6:29pm. Unfortunately another gap in the service left us with a 10 minute wait here too. Perfect Morden connection at Kennington, and Brixton connection at Stockwell brought us back onto a Morden train at 6:55pm. Stockwell - Morden and then double back to South Wimbledon, arriving at 7:20pm, with now 16 perfect connections under our belt.
A lucky wayward 57 meant that South Wimbledon - Wimbledon Connection was completed with 7 mins, unfortunately, as I approached Plat 1-4, I saw the Edgware Road train I needed pull out. That meant a 5 min wait for a HSK service.... We arrived at HSK and waited for the circle line down to Paddington.
We were now in the homestretch, with only the Bakerloo and Met needed to complete. At Paddington, we caught a southbound Bakerloo to tick off Bakerloo Edgware Road and Marylebone which we missed from earlier. A perfect double back at Marylebone dropped us off at Queen's Park in time to catch the 20:24 LO to H&W. As we pulled into H&W, the southbound train was on the opposite platform. Fortunately, it dwelled long enough for us to make perfect connection number 18 down to Kenton. A quick 4 min run down to Northwick Park left us with an unusual 4 min wait for a southbound service to Preston Road.
Another long wait at Preston Road for a delayed Watford service brought us to Watford just after 9:35pm. As per the timetable the train should have left at 9:38pm, but perhaps due to technical issues, we only left at 9:45pm. Fortunately, this was just enough time for me to break my journey and still catch the 9:53pm Chesham service. Last 2 trains to go.
We departed Chesham right on time at 10:26pm and Metropolitan 465 brought us into Amersham 1 minute late at 22:54:50, giving us a total time spent of 17:51:55.
I firstly cannot emphasise how lucky I was on this day to be able to make 18 perfect train connections out of the total 55 trains I used throughout the day, furthermore, I was extremely happy to break the 18 hours barrier (firstly as it seems as nobody has done it before, so I can claim the unofficial record even just for myself should I not have enough evidence to provide to the forum

I am tempted to try this route again, but maybe modified against any changes to the timetable in the Spring, it is simply too depressing and cold to run during the long winter nights. But I do have full belief, that this route, if followed perfectly, can grant a sub 17 hour time (even though theoretically a sub 16 hour time should be possible with a more efficient route due to Andi and Steve's record of 15:45 in the 270 stations format.)
Does anyone have any idea of what this sub 16 hour route may look like? (if you are willing to share of course

