What's the Name of That Book??? discussion

A worker goes to stay in a boarding house in a seaside town. It is set sometime around the 1940s to 60s. The protagonist gets upset at another tenant. In the night, he creeps into his room and bludgeons him to death with a hammer. He then goes on the run. The newspapers describe him as a monster. The book is written from the point of view of the murderer, who feels his victim brought it on himself. The murderer feels that he ist the innocent party, and that the manhunt and the terrible things being said about him are unjustified.

What country?
Cover?
Author's gender?
When did you read it?
When was it published?

Could this be the same book William is searching for here?

https://www.goodreads.com/topic/show/...

William thinks his book was This is How.

It’s from the POV of the murderer and though the time setting doesn’t seem to be clear, reviewers put it between 1950s to 1970s.

A Guardian review states:

“Patrick Oxtoby stoves in the head of Ian Welkin (a fellow lodger in his seaside boarding house) with an adjustable wrench in a moment of – not exactly madness, but unusual behaviour – that changes the course of his life and ends another.”

“Patrick is so unable to understand why he acted that he continues to maintain his innocence to the reader and to himself (as well as in a tense and expertly dramatised court case) until deep into the book.”