Is there any independent corroboration for these claims, though?
My thought exactly. Pertwee would have been only about 25
when the war ended, and the Daily Mail is perhaps not he most reputable of sources.
Without getting into the actual claims that in itself would not be usual.
Age-wise, it was not uncommon for young personnel to get promotions if they had a 'knack' for special duties.
I just find it more amazing that prior to WWII, he served on the ill-fated H.M.S. Hood
, and had he not been re-assigned, he could well have died when Bismark
sent her to the bottom.
As he lost a lot of friends on that ship, it could well have been a motivation for him to give it his all.