What makes a classic?

To celebrate its 15th birthday, Vintage (Random House's literary paperback imprint) has presented reading groups across the country with a list of 100 titles from the last century (take a look at it here) and asked them to predict which 15 will be hailed as classics in the future. As with any list like this, the first thing you notice is not what's on it but what's missing. This list seems to be heavily tilted towards the second half of the 20th century, for one thing, and there are some odd inclusions (Politics by Adam Thirlwell - really? Anything to do with the fact that he's on the Granta list? Atonement, out of all of Ian McEwan's books?) and omissions (literature's current prince and princess of cool, Dave Eggers and Zadie Smith, are both conspicuously absent) – but there are plenty of worthy titles on there, too. I'd personally plump for Iris Murdoch's The Sea, the Sea, Utz by Bruce Chatwin and probably I Capture the Castle by Dodie Smith as three that I'm sure will be being read in 100 years time. What do you think?