Thanks to you both.
The manual says "FORMAT 3 will usually be selected automatically, if this is not the case you can select it yourself".
My source is a Sky digibox set to 16:9.
I know I can set it myself, but am confused by the word "usually" above. Either it will or it won't I would have thought, unless it is suggesting the format setting will be dependent upon other factors.
Haven't got a spare scart lead, but suppose I could buy a cheap fully wired one (I hope fully wired) and see if this achieves what I want and if it does then get a better lead.
Unless someone has a different idea. Please feel free to suggest!