You'll need to add a cheap SIM to get this delivered for £13.44. Comfortably cheaper than elsewhere.
This Jabra BT5020 Mono Bluetooth Headset has a behind ear design with up to 10 hours standby time and up to 300 hours talk time. The Bluetooth headset features a 10ft operating range, volume control, mains charging with charger included, Led indictors and last number redial. It also includes call hold or call wait function and an answer or end call button.