Not according to the NHS Bone marrow directory - http://www.nhsbt.nhs.uk/bonemarrow/qa/index.asp#howcan. This says you need to be between 18 and 49 to sign up. As far as I'm aware, the data on potential donors is shared between this and the Anthony Nolan Trust so it shouldn't matter which one you sign up to.
You do have to be a blood donor to sign up to the NHS register so it's still restricted and if you can't donate blood for whatever reason then you won't be able to join. But it's worth a go anyway.
Press Release Arc'teryx Climb Academy returns to the Lake District: May 25th – 27th
Podcast Mountain Air - 16. Patrick Davies: The Diplomat Who Walked the Length of Britain
Gear News The Art of Climbing – Out Now
Fri Night Vid Siurana - A Limestone Paradise
In this week's Friday Night Video, we follow Robbie Phillips and friends to Siurana, Catalunya, where he aims to regain some sport climbing fitness to tackle James Pearson's Le Voyage. It had been a decade since Robbie had been on a Spanish bolt...