well this is probably very bad form (to reply to my own question) but I found the following –
‘Look at your most healthy heavily cropping plants; and take some cuttings (as in the side shoots I assume) from them.
Pop them into modules around about now, and let them recover. [They flop for a week, then stand up and carry on growing]
Slow down the watering and when late autumn comes, take the strongest few indoors, and grow them on in a cool [not too warm] position.
Then, pot them on around February time, and grow them on next year. ‘
so I am going to try as I have several tomatoes who do not want to fade away!