A tricky one, I recently had an issue about this with my nanny. She was seen by my neighbour hopping back into the car with milk and bread. The children would have been alone for at least 1 minute. I raised the issue with her and she said she can see the car the entire time from within the shop and the car was locked. Since this happened we just make sure we have bread and milk in so she doesn't have to do this! Not sure on the legalities! Common sense more of an issue. Thanks Frances