Andy you have just been Christened into the pig club! Now as a full member you too can enjoy the benefits of high blood pressure, leaking wellies and wonderful skin from all the mud baths. If you survive to become a senior member (need at least 100 hours of pushing pigs where they dont want to go) you get the medal (or a hot bath and a bottle of liquid soap).
As Kate says they will normally follow food. If you have electric fencing was it the imaginary line where the fence was that they would not cross. If so put straw across that area, follow Kate's advice on the food trail. Maybe dont feed them the night before moving, dont put food into the field at all. If it is the fence that bothers them, once they get the idea of moving outside to eat they should move.
If they are quite small you could always wheelbarrow them that is grasp back legs firmly, walk backwards, pig follows on front legs. Very noisy, cold , guaranteed to cover you in mud.
I have found leaving the gate open, the food outside, sitting with a flask of hot tea and a book helps. GOOD LUCK