According to TFL Twitter, the current departures of S8 trains from Amersham are XX.00 and XX.30 past the hour. They have also told me that the earliest touch in for an Off Peak fare is 09.30, therefore the 10.00 departure is now the first Off peak train (unless the 09.30 departs late).
I’m sure that previously I have caught a train before 10.00 (possibly 09.28?) and been charged an Off Peak fare. I also thought that earliest Touch In time used to be earlier than 09.30.
Off-peak fares start being charged at 0925. This is an unpublished grace period which was confirmed in response to an FOI request. I’d leave touching in until 0927/0928 as long as the train leaves from the usual London bound platform.
Yes, that’s right. But if there’s a chance you won’t reach the cap then note that it’s the peak fare you’ll be charged. If there’s no train to catch between 0910 and 0925 then you’re probably better off waiting.
Yesterday lunchtime the Met line trains were all leaving from platform 2, where they normally arrive on the other side of the bridge from the entrance (albeit at xx22 and xx52 past rather than the advertised special timetable of xx00 and xx30). You might not be able to cut it as fine as 28 past to tap in get on the half past train.