Green’s Dictionary of Slang

1. an eccentric.

1916		G. Squiers Aerbut Paerks, of Baernegum 9: ’Ush, yer barmpot, it’s in ther saervice.
1951		J.B. Priestley Festival 33: Lady Barth, a rich old barmpot who, probably because she had nothing else to do, was always either buying and selling property.
1962		K. Waterhouse There is a Happy Land (1964) 65: ‘G-i-ive o-v-er, Barmpot!’ I shouted.
1975		(con. 1939) J. Rosenthal Evacuees Scene 20: You barm-pot! He’s got foster-parents already, in Manchester!
1976		J. Rosenthal Bar Mitzvah Boy Scene 73: Eliot. Barm-pot. To you I seem like a God ... a hero. It’s only natural. Natural but stupid.
1996		S. Townsend Adrian Mole: Lost Years 174: Bianca described him as a ‘barmpot’ this morning — but as I pointed out to her, Jesus himself was reviled in his day.
2005		A. Tan Saving Fish from Drowning 243: What else could he say to set himself apart from that barmpot on the other channel who also called himself an animal behaviorist?

2. attrib. use of sense 1.

1968

P.H. Hall India Man 82: And to toll out the Riot Act to a lot of barmpot Micks.