I passed it on to the translator I work with and he told me it made
him get
"How to be Topp" by Geoffrey Williams and Ronald Searle (first
published
1954) from his bookshelf. The text seem to mimic the style of that
book, and
the main character in it is called Nigel.

It does read in the style of the Nigel Molesworth books by Willans and
Searle, but it's clearly based on a modern scenario, which leads me to
suspect that the author is probably Alan Coren. I've seen him parody
the Molesworth stuff before, and the parody is very much in his style.

(On topic: Alan Coren has written many books of short humorous
articles. Once, he approached the UK's biggest bookseller, WHSmiths,
and asked them what books were consistent bestsellers. He was told that
books about the Third Reich, books about golf and books about cats
always sold reliably. Hence, he titled his next book "Golfing for Cats"
and printed it with a swastika on the cover.)

Cheers
Al.