The hot water has just stopped running - it starts very slowly and then trickles down to nothing.

Where could the fault be, should we get in a plumber?

You have to give us a little more information than that. Does that happen at one faucet or every where?

Every tap and the washing mashine tap, I just noticed that one day I turned on the hot tap to fill the sink and it slowly started to dwindle to nothing, I thought it was because the washing machine was on, but then it was happening all over the house.

Have you had any plumbing work done in your house in recent days ?

Remove a aerator from a faucet spout and tell me if there's any crud caught in the screen? How old is your home? What type of pipes? Copper, plastic or galvanized? Do you flush your heater out on a regular maintenance schedule? Let's have more details. Tom