Thanks all ... general opinion then is to carry on and turn them over which I shall continue to do. Sadly, the option as sleeping as singles won't do as my Son and my parents (well Dad, not Mum) are too long and their feet would hang over edge. However, if I can find another memory foam topper at £30 like I did at Poundland Plus in April, then I will purchase and keep rolled up to place on top of cushions (they're not having ours off of our bed lol).
Keep a couple of lovely fawn tactile throws over the seats when bed not in use as quickly learnt that spills better to clean off washable throws than seat cushions.
... and Lord B ... don't have any dogs to take out for night time piddles - only an OH and a teen - do they count????