I have tried holding it a really long time. I have also taken it to the local Ford Dealer, who have plugged the computer in and looked at all the country settings etc, to make sure it was still set for the UK market. They said that it was not possible to change between Miles and Kilometers without changing the country setting. I'm going to try the Disconnect the battery, then reconnect with the trip reset held in, but hold it in for a really long time, like 2/3 minutes, if my son's finger can hold it that long! NikpV- thanks for your rapid response to this question! As a newbie I did not realise there was so much help out there