Where can I turn off the mains water supply in the event of an emergency?

For the most of the properties in the midlands The main stop tap cock for the property should be located either in your garage (if you have one) or under the kitchen sink, if you cannot find it in these places there should be a cover on the front of the property on the footpath this will need a stop tap key to switch this one off. (But you maybe able to reach this if you have long arms)