Now as a very young man with BOAC in the early 60s I seem to remember that the Britannia 102 had square tipped hollow blades whereas the 312 had round tipped solid blades.
When BKS operated the 102 they had square blades but near the end of their life you would see them using the round solid blades, presumeably because the hollow ones were becoming hard to find.
Now from the pictures above it would seem that it was allowable to use, in matched pairs, either type prop on either model.
Being a Comet 4 boy at the time I was not that close to the Brit, but I seem to remember that other than the corrosion problem with hollow blades they were also very sensitive to Foreign Objects damage as unlike the Dural blades you could not dress out nicks in the blade.
Some good photos thanks
