"For New Aircraft Types"

This is a drawing in the back of a book I bought from a car-boot sale yesterday. The book is fascinating in itself; published in 1941 it's called "The Spotter's Handbook", and was intended to train aircraft spotters - along with the war-time Civil Defense authorities - to tell the difference between British and German aircraft.

It's fascinating for so many reasons. In the opening cover, this copy has a hand-written inscription, written in fountain-pen, "Best Wishes From Dad Jan 30th 1941". Was the recipient a spotter? You can't but help wonder what happened to the father, or to his son who may well have drawn this aircraft's outline.

But what's most interesting, to me, about this picture is this from Chapter Six of the book:
If any new type which has not been described in this book begins visiting Great Britain, the reader is recommended to make a drawing of the 'plane like those given in the book and to determine its salient characteristics in the same systematic way.

The drawing is clearly in keeping with this advise. However, I can't help but wonder; to me this looks like a Messerschmitt 109 without the tail-plane struts - but the 109 is one of the aircraft described in the book. Could it be that whoever owned this book during the war was drawing a Focke-Wulf Fw190? Or was he simply practicing his drawing skills?

This book has been a treasure-trove of delights, but none more so than this. Who owned this book? Were they a spotter? And why did they draw this picture?