Is it normal to sign land registry owner transfer papers for a house sale before the sale is confirmed ?

Martin asked:


A relative has signed papers for land registry transfer to a prospective purchaser and sent them back to the solicitors without an agreement or confirmation of a sale. I am concerned that this might pose a risk over property rights at some point. Am I correct or worrying for no reason ?
Thanks for your answers, by the way - this applies to the United Kingdom.

Miriam