The Victorianesque language slips from time to time, but this is grand rollicking adventure, full of in-jokes for those with a knowledge of Egyptology or of the history and literature of the period it deals with.
The blurb has got one of these wrong: it's not Sir Henry Baskerville who has died, but Lord Baskerville "of the Norfolk Baskervilles, not the Devonshire branch of the family" - that is, a distant cousin of Doyle's Sir Henry. He's not the only Sherlock Holmes character to be referenced - there's a Von Bork here, and a Charles Milverton, both very different people from their villainous namesakes but a joy for a Holmes fan to read about.
Anyway, these people inhabit a gloriously silly plot which has been uncharitably but not altogether unjustifiably compared to a Victorian-era Scooby Doo, with fake ghosts, a mummy's curse and a long-lost heir. Melodramatic? Yes. Implausible? Certainly. Tremendous fun? Undoubtedly.