They always say that writers should write about what they know and you can tell that Patrick Hamilton knows a great deal about pubs.
As Miss Roach gets involved with an American based nearby she is dragged into the pub on a regular basis where she is given large gins and kissed by the drunk solider. She is both afraid but excited and she views the relationship as one means of escaping from the dreary world of the boarding house.
Where Hamilton is excellent is building up a detailed picture of a very small world – in this case the boarders at the Rosamund Tea Rooms – and as a result being able to transmit the significance of what otherwise would appear trivial and mundane.
Therefore you realise just how desperate she is to escape from her situation and her life, penned into the suburbs because of her fear of the blitz.