The whole situation with Nigel Stepney seems to have become clearer over the weekend.
What we know:
1) Stepney gave Ferrari information about car design but also about race procedure to
Mike Coughlan (this seemed odd, what procedure could McLaren possibly learn).
2) We know that Stepney and Coughlan are good friends and we now know that they wanted to go and work for Honda together (a team that do need new technical details and procedures)
3) Somebody outside F1 tipped off Ferrari.
My guess is that this person outside F1 is Ross Brawn. There have been a lot of rumours that he has been linked with Honda. I think Stepney and Coughlan heard this and wanted to go and restart a dream team. They probably had the documents collected so that they could then get this package off the ground. They probably then heard the rumour that Ross was actually going to Ferrari, and contacted him to talk about their plans. Ross probably immediately contacted Ferrari and that’s where it all started from. Obviously this is just my guess, it seems to make sense though.