I think it's an Italian BB thread. 36x24T
Almost certainly Italian made then! Maybe compare with some frames by Losa (he built for many brands including his own)
The lugs & seatstay join kinda reminds me of his work
Raleigh SBDU built some lovely track frames with Cinelli lugs & BB shells, so could be a possibility. They usually go for serious monies too.
@Nbenja3 started
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I think it's an Italian BB thread. 36x24T