✔ 最佳答案
I think there is no any responsbility to be taken & don't worry.
1. No formal S & P document to prove this transaction.
2. No property agent act as a witness.
3. No deposit you have received.
4. You just assign a solcitor to prepare a formal S & P. Acutally, you are the client of solcitor therefore you can inform her to cancel this documents. (the documentation fee or search fee to be paid to the solicitor)
According to you informations, the buyer can prove the intention of you in this transaction but no evidence in the overall deal. Surely, the oral committion is legal binding. I suggest you should explain your reasons to the buyer directly.