| 20th October - 21st December 2007 | Low | £240* |
| 22nd December 2007 – 4th January 2008 | Medium | £320 |
| 5th January – 14th March 2008 | Low | £240* |
| 15th March - 11th July 2008 | Medium | £390 |
| 12th July - 12th September 2008 | High | £580 |
| 13th September 2008 - 10th July 2009 | Medium | £390 |
*Subject to heating surcharge