Outdoor tap cut off by work done by neighbour

My property has an outhouse which is joined to next doors outhouse. Both have had water supply to each outhouse since the properties were built in the 1930’s. The water supply to these outhouses are not supplied by the main water supply.

I have been told by neighbours who have lived in these properties since the houses were built, that they had sinks to wash clothes. 

Last summer, my neighbour reported a leak to his outhouse and was told that as this was on his property it was his responsibility to arrange to have it repaired. He subsequently got a contractor who repaired the leak, cutting off our water supply to our outhouse in the process. When we challenged this with the contractor we were told that as the outside tap was unknowingly drawing water from my neighbour’s property it appears to be an unauthorised connection.