Am seriously confused now.
We are about to draw a line in the sand for exchange with our vendors as they are pratting us about. We know why: the top of the chain (to which bear in mind they're effectively committing US!) is becoming protracted (something about surveys taking more time to arrange in Cornwall??).
We are buying off Party B. They've had an offer accepted on Party C's house. Party C have had an offer accepted on D in Cornwall which is an end of chain.
The vendor's EA tells us today (6 weeks after acceptance) that all parties in a chain conventionally exchange on the same day.
Well, surely Party B NEED a guarantee of our money via exchange in order to pay Party C who can then pay Party D?
Surely WE need to exchange 1st?