A warm welcome to the forum

You can indeed enter the championship at any time you like and take part in as few or as many R15's as you want....
Yeah we either meet in the entrance hall or just outside, if it was a station like Oxford Circus then we would definitely specify a specific entrance, we are normally quite easy to spot anyway

The whole thing is done on trust, you start your watch when the envelopes are opened and stop the watch when the doors open at the last station you visit, hand your time to the BERC at the pub and let him know if you are playing a joker or not..
We have run a poll to detremine start times and it's not always fixed at 12:00. It has been later on other occasions
Quite a few people go solo so I am sure that a team mate could be found at the start for you

Well who knows what will come out the "randomator" there is a possibility that an upcoming round could include Z3 stations and also the Overground and we have already done one with the DLR.... A bulk standard R15 has no fixed starting station and they are all tube stops within Z1 & Z2..
Hope to see you in Jan
