Hilaire Belloc 
A Change in the Cabinet 

That rare thing, a pure political novel. Belloc boasted that in it, politicians talked as they really do talk (or did in the first decade of the twentieth century), which he said caused great shock among readers. It's a slight thing, but funny, a bit fantastic, with a nautical excursion, and great realism – so after you're tired of re-reading the Palliser novels, it awaits you.