Agreed with OWD on this. Many H&H and Boss (and others) have dovetailed lumps, especially post WWII or pre 1900.
The (only) way to know who made the barrels is to ask H&H.
Dovetailed lumps are by no mean a Brummy thing, no more than chopper lumps are a London one.
The most expensive guns usually had chopper lumps, but that's era dependent as stated above.
Best regards,
WC-