The number given above is correct and you're sometimes cheaper getting one at the likes of Boots the Chemists or a local ironmongers or whatever rather than a PC shop. Some PC shops charge the earth for one, not all of them, it is worth checking as one shop here charges £2 odds the other wants over £5 for the same battery.
Thanks to all who answered. Currently live in Cyprus, but will be in England next few days for a short time, which is why I don't have time to take my system apart just now: too busy trying to organise the itinerary. And also why I need a new Cmos ( no, I never needed one before in 30 years of computers!)The combination of power overage/underage/not at all and the dust, are both lethal....... Do hope I booked the right flight on line... Thanks again Kim