Anyone who watches television over Freeview - whether through a set-top box or special TV set - will need to re-tune their decoders from lunchtime on Wednesday Sept 30.

The change is necessary to ensure that viewers keep receiving Five, and to pave the way for the supply of high-definition (HD) television.

Specific instructions for updating particular makes and models are available on the TV Re-tune website, but these steps should work for most people:

1) Switch on your Freeview TV or box

2) Using your remote control, press 'menu'

3) Select the 'set up' or 'installation' option

4) Press 'OK'. If your equipment asks if you want to delete all your channels, don't worry, that's normal

5) If you are prompted for a code, try 0000 or 1234

6) Channels will be automatically installed. This may take a few minutes and your equipment may shut down and restart

7) After re-tuning, you may reset your 'favourites' list. When you re-tune a digital TV recorder, you should re-set future recordings

8) Remember to re-tune every piece of Freeview equipment you have.

People with Freeview-based television recording services like BT Vision and TopUp TV will need to re-tune their boxes, but satellite viewers are unaffected.