This is a decent Biggles, but by no means one of the best. As has been pointed out by others, the long lecture about counterfeiting at the beginning was a bit off-putting, and unnecessary. Everyone, even back in the day, knew what counterfeiting was. And as has also been pointed out, it is extremely unlikely that Ginger could fool lifelong hunters with his ferocious lion imitation. However, you just have to suspend belief for awhile and go with the flow, otherwise poor Bertie is up for the chop.
It does seem like Johns kind of breezed through this one, and it was a bit sad not to have seen more of Biggles in this book than we'd like to have. There aren't a lot of twists and turns in the plot, but it is still a good story nonetheless.
A word of advice to all; don't read books from the 1920's-1940's and then be "shocked" that you found racism or sexism. Not all the characters are going to be modern and liberated by the standards of 2022, and not everyone is going to live together in colour-blind peaceful harmony. This was the way the world was like, so if it upsets people to read about these things, stick to contemporary books. Poor Johns is long gone, so there is no point our giving him a piece of our minds about life in 1948.
If this was your first Biggles, you can look forward to even better stories!
Enjoy!