Well I've had the day and they've said I'm definite to stay to next Friday to start off with, ie a week and a half when done. I was on phone sometimes but don't have to do the most difficult communication and do not answer external calls. I do make some calls to applicants' stated workplaces to establish that they genuinely work there and ask them other "security" items, but this isn't confrontational like the suppliers of the place I was at in January. My supervisor understands I may need to pass a difficult call to someone with more authority and experience to know what to say.
The train journey back was a tad crowded, but then I expected that. Still I'm sure it wasn't as bad as driving into that city would have been, and the office didn't have many allocated parking spaces anyway.