Anthony Phillips - The Geese & The Ghost

Artist: Peter Cross

Trouble for Trumpets (1982) and Trumpets in Grumpetland (1984)

There is lot of background and info on Peter Cross' website so I encourage you to explore.

The books are difficult to find these days but are currently available to check out on Internet Archive:

Trouble for Trumpets (1982)

Trumpets in Grumpetland (1984)

The two books follow the life of Podd (a Trumpet) and later his friend Livingstone, the Queen's lute player, as they thwart the evil plans of the Grumpets (essentially Nazis, no I'm not joking). The books contain an incredible level of detail, featuring highly realistic animals in addition to the charming Trumpets. Aside from the great stories, they are also like the I Spy book series but with art akin to Beatrix Potter or Jill Barklem. Peter Cross created the art and Peter Dallas-Smith created the cohesive storylines.

Look at these amazing covers!

Trouble for Trumpets, page 10-11, top left (slightly different in the book):

Trouble for Trumpets, page 22-23:

Trumpets in Grumpetland, page 8-9

A picture of one bit I like very much (page 7):