Lorna,
Potentially Interfering with a motor vehicle is the offence, unless any damage has been caused. However, normal procedure for such things is for cones to be placed and a notice put in position. Vehicles at the location 'should' be noted that they were there when the notice was placed, anyone parking there after this time could be subject to a penalty notice. If the works are legitimate and prior warning is given, then Councils or the Police may move a vehicle if it is causing an obstruction. No come back for the owner, as long as they can prove steps were taken to warn residents that work was due to take place and no damage is caused.
From what you have outlined, it appears they may have had the right to move your car. Very annoying I know, but we as the public do not 'own' the highways and only have a right to use them, as long as we comply with legal obligations (insurance, tax etc).
GG