You don't say where you are in the country, but dryness at the roots last summer and autumn may have contributed, if you did not water.

And the heavy frosts if you are in the northern part of the country.

Thanks a lot for your comments, I'll ensure it gets sufficient water and feed. It's funny as my other bush is fine and has flowered for the last couple of years, although it is a few years younger.
I'm from Durham by the way.

So lack of water isn't likely to be the problem. Is it in the ground or a container, if the later have you been feeding with an ericaceous feed? Is your soil acidic or alkaline?