Cant get identity verified as have no contact details the former leasholder

Commercial leased surrendered in 2020 amicably between freeholder and leaseholder. We did this ourselves on the correct form and was witnessed. We didnt know that identity had to be verified and a form completed for that.
Now selling property but lease still shows on land registry. To remove it I understand that I need the former leaseholder to have identity verified. However I cant do this as I have no contact details for them  What can i do?
In the meantime the property which was commercial has been changed into residential and it it is the residential lease we want to sell but think their solicitor will query it because it still shows a current commercial lease which expires in 2027

Claire - identity verification for registration purposes is usually only required if the lease has been sold/transferred, not surrendered. 
Section 4 - Evidence of identity (PG67) - GOV.UK (www.gov.uk)