Strolling around the village I saw a man working in the street. The van had a Humberside Fire and Rescue logo and the man was fixing a hydrant sign to a wall. A quick chat established that he was checking they were present and replacing imperial hydrant signs with metric ones. I asked him if any data about the location of the hydrants is available. He said he would ask someone to call me about it.
A little later I got a call from HF&R. I asked if the location of fire hydrants was available and was told in no uncertain terms that they were not. I explained about OpenStreetMap and the caller told me that OSM had no reason to add hydrants, adding that their locations are confidential. When I said that as the data is not available I would just continue to add the ones I see as part of surveys he repeated that their locations are confidential and added that they belong to Yorkshire Water, the local water company. He asked why I wanted to put hydrants into OSM and I told him that such details make a richer map.
The locations of hydrants are hardly confidential, there is a yellow sign showing where each one is. I was a bit surprised by the HF&R man's indignant reaction. It does seem that the notion of opening up data has not reached into that public body at all.
I have only added a few hydrants experimentally and stopped because it didn't seem worth the effort. I may add a few more, but not, it seems, based on HF&R data, and only under the cover of darkness.