Things learnt:

• Stuff happens. In this case, a medical issue I had no control over and which would probably have caused me significant injury if I had continued. Sometimes you just have to call it.
• Carry food. Even if the controls are supposed to be able to feed you, things do not always go accordingly to plan (two controls have run out of their planned food already – and that's before anyone gets there southbound)
• Test everything completely. I did the first stage from a routesheet because the gps file somehow didn't make it onto my account – I suspect it got deleted by mistake when I updated another file.
• Don't try and fix a valve problem on a tube, just replace the tube immediately – although that second tube also went flat overnight, damnit
• Don't forget your buff. A door frequently opening into a well-lit corridor does not help sleep
• Market Rasen station has a track crossing to get from one platform to the other. I didn't think those existed in the UK any more!