Looks rather like its going to be a N.U.T - Newcastle upon Tyne,
that cast alloy muffler under the engine is very distinctive.
Painted nut brown in its original finish.
Likely to be a 1000cc JAP vtwin, might take some figuring out precisely what year it is,
but circa 1920 or so.
Quite an expensive motor for its time, quite popular too.
Electric lighting would still have been quite a novelty at that time.
Could only find a small pic, will look for a bigger example.
Cheers.