Greetings peter
A bit of a poser.
It appears that Fairmile’s was an organisation that developed/designed a form of pre-fabrication in a method for building sea-going vessels in WW2.
They appeared to not actually build the vessels themselves.
From various sources I have found the former Vegea was referred to as Fairmile ML 022.
In another reference I have found a Fairmile ML 033 described as a “D” {DOG) Boat which was built at Brightlingsea.
This numbering does not correspond to the actual Royal Navy boat numbers. Possibly they are the builders yard numbers.
Aldous Successors had a yard at Brightlingsea, and built 10 Fairmile “B” type, but there is no reference to a “D” type.
Details seem incomplete and don’t match up.

Good hunting

Phil