Ordinarily I would say there is no particular need to have a Solicitor involved in the booking deposit, which this is. Normally pay to the sales agent and get a proper receipt. As per others it should be a modest amount.
However, if I was you, in this case (for peace of mind as much as anything else) I would route the money through your solicitor. You will need a solicitor anyway to handle the purchase so not a big deal for them to send the deposit. The reason I say this case is a little different is due to the seller being bankrupt. I'm not a solicitor so I dont know what exactly the legal position is but you would not want to find yourself in a position where you paid the deposit, it goes to the seller or is held to the benefit of the seller and it somehow gets 'mixed' up in the whole bankrupcy situation.
Best to avoid that even if there is a remote chance - why take one? Better to talk to your solicitor, at the very least to see what the story is.