There are products that allow you to verify a person's identity electronically. You should check with your professional body that these products comply with your professional body's rules on money laundering and your duties under statutory money laundering requirements.
The changes will not alter the requirements set out in paragraph 14.1.1 of the Handbook which require the conveyancer to register the mortgage as a first legal charge at the Land Registry. Lenders do not regard the retainer as being complied with until this is achieved.