One of the great things about the arrival of the slightly better HTC Sensation XE is the volume of deals we’re now seeing on the original HTC Sensation. You can currently grab one from PrePayMania for £327.78.
The HTC Sensation comes SIM free and unlocked, so you can jam any old SIM card in there. Giffgaff is probably your best bet.
(Thanks to jopilar at HUKD)