Definition of "gamp"

It was the last day of the match, and owing to rain it was really unfit to play, but the promoters insisted upon our doing so, to satisfy the spectators, who stood round the ground with their umbrellas up. […] One gentleman sat with his gamp up on some rails near the railway.

1900, A. W. Pullin, Talks with old English cricketers, page 169

And it was early morning, and the world was moist, when the crystal-gazer's husband, a freak in knickerbockers with an open coppish and a sabbath gamp, came over the stones outside his house to meet the holy travellers.

a. 1954 (date written), Dylan Thomas, “The Holy Six”, in Adventures in the Skin Trade (A New Directions Paperbook; no. 183), New York, N.Y.: New Directions Publishing Corporation, published 1969, page 129

In his hand he waved – an appropriate symbol of disapprobation – his London gamp meticulously rolled.

1983, Lawrence Durrell, Sebastian (Avignon Quintet), Faber & Faber, published 2004, page 1111