« Reply #3 on: Sunday 02 December 18 04:13 GMT (UK) »
There are images of blank British Deed Poll Application forms online and there is no reference to the parents of an adult. The only reference to parents names being required is an application to change the name of a minor under the age of 18 years.
Unless you require a legal name change for a passport, driving licence, etc., you don't need to go down that route.
Here's a website that answers many questions, and yours is Question 10:
"Q10: I am trying to find a record of a relative's name change. Can you tell me if they have changed their name by Deed Poll?
A: Searching for someone's Deed Poll is like looking for the proverbial needle in a haystack. This is because there is no central register of all name changes by Deed Poll. Furthermore, in addition to ourselves, a Deed Poll can be prepared by any of the many thousands of solicitors in the UK and there are other websites providing the service. Even if you discovered who prepared your relative's Deed Poll, client confidentiality prevents the disclosing of any information about the Deed Poll.
The only chance you have of locating a Deed Poll is ...... "
http://www.deedpoll.org.uk/OtherFAQs.html
Aberdeen: Findlay-Shirras,McCarthy: MidLothian: Mason,Telford,Darling,Cruikshanks,Bennett,Sime, Bell: Lanarks:Crum, Brown, MacKenzie,Cameron, Glen, Millar; Ross: Urray:Mackenzie: Moray: Findlay; Marshall/Marischell: Perthshire: Brown Ferguson: Wales: McCarthy, Thomas: England: Almond, Askin, Dodson, Well(es). Harrison, Maw, McCarthy, Munford, Pye, Shearing, Smith, Smythe, Speight, Strike, Wallis/Wallace, Ward, Wells;Germany: Flamme,Ehlers, Bielstein, Germer, Mohlm, Reupke