Hi Mike, thank you for that. Apologies for delay in responding.
Re. router model, I've checked on the machine itself and it appears to be a Thomson Gateway TG585 v7. I'm assuming that the v7 refers to the software update state?? I've had this router operating since changing to Plusnet in May 2010 and haven't bothered to check for s/w updates nor would feel at all happy at attempting it. As I wrote previously, 2 out of 3 will do quite nicely for me

The Advent must be close to 20 years old and way beyond its 'sell by' date! Just remembered, a propos nothing - I paid just under £1700 for it at PC World - not sure whether the price or sale venue represents the greater madness!!