.
...FWIW, while I have no idea of what your bike might have been, or when it was made, Carlton used those Capella lugs on their bikes for a number of years in the 60's.

Here's one from 1965:
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But with a Raleigh head badge, probably 1973, when someone seems to have decided to use them all up.

Edit: just saw your last photo, clearly a Competition, like this one:
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