The sub in the photo is def an Upholder from OTW.
All four were sold off to Canada to become their new Victoria Class SSK (diesel electric hunter killers)
Nothing to do with the Astute class SSN which are nuclear hunter killer subs with cruise missiles (similar to the improved US Los Angeles class)
Vanguard as just SSBN ballistic missile subs, a nuclear deterant force, and carry out a totally different role from the hunter killers.
Regards
SteveJ