To Say Nothing of the Dog

By Connie Willis
It's one of those books I've been vaguely thinking I should read for years. It won the Hugo back in 1999, which is usually a reasonable indication of quality, but I was spurred into finally reading it by an interview on starshipsofa.
It's a great book. I really should have read when people first started praising it.
In the late 21st century time travel has been perfected, though rather to the disappointment of the big business types who funded it, you can't bring stuff back, and the laws of causality prevent you betting on the 1888 Grand National and investing the winnings with compound interest. At least I assume they do - I don't remember it being mentioned, but if the time machine could get you rich that way the rest of the book wouldn't make much sense.
So there's a time machine, and the only really useful thing you can do with it is send historians back to get some first hand evidence on what they're studying. As the book starts though the entire Oxford University history department is in thrall to the hugely rich Lady Schrapnell who is obsessed with rebuilding the bombed Coventry Cathedral, and demands it should be exactly as it was hen destroyed, and in particular feature a lost piece of statuary known as the Bishop's Bird Stump.
The hero, Ned, has been sent on so many trips through time that he is completely befuddled, and is despatched to the late Victorian period to undo one of his fellow's mistakes, and more importantly hide from Lady S until his nerves recover. Being befuddled, within fifteen minutes of his arrival he has put in place at least half a dozen paradoxes to further complicate the web of history. It all gets very intricate, with Ned fretting terribly as he is dragged off with two others (and a dog) on a boat trip down the Thames.
There are mad professors and murder accusations, assignations and romances, in which the wrong people insist on falling in love, and several groups of historians working at cross purposes. At one point, Jerome K. Jerome is encountered working his way up river and Ned & co drft down. All very involved and very clever. And funny.
I'll certainly be looking out for more from Willis.