(There are probably some very minor spoilers in this.)
It's a direct sequel to her 1992 Hugo winner Doomsday Book, which I recall was also rather irritating.
The first problem is that while it's allegedly set in Oxford in 2060, it's actually set in the 1980s or thereabouts. All the characters are continually running round Oxford looking for each other, and/or receiving garbled messages, because no one has a mobile phone and no one has email (or at least, they don't use them). You could just about get away with this in a 1992 novel, but you certainly can't in a 2010 novel.
Second, she hasn't really done her research (again). Inability to use Victoria station wouldn't be much of an impediment to getting round London in 1940, when it was only on the District line and wasn't an interchange. There aren't any garter snakes in England. Nor is there any skunk cabbage. London is not laid out in blocks. Russell Square Tube station was involved in a terrorist incident in 2005, not 2006. No English person who's studied crosswords in the history of games could be unaware of the existence of cryptic crosswords, even in 2060. Charing Cross wasn't the right Tube station for Trafalgar Square in 1945, because it was what's now called Embankment. What's now called Charing Cross was two different stations called Trafalgar Square and Strand, and you'd have used one of those for Trafalgar Square.
Authors, if you're going to set a book in a country that you don't live in, try to get a native to read your book before it's published.