This 12-month SIM only deal from Vodafone is currently half price. Usually it's £20.50PM, but you can grab it for the significantly sexier price of £10.25PM.
The monthly allowance is 900 minutes, "unlimited" (i.e. 3,000) texts and 250MB of data.
Not available online, but call 08080 101 257 (option 1) and they'll hook you up. Expires soonish, but quote the HUKD deal and you should be sweet.
(Thanks to jimbohigh at HUKD)