A couple of observations... shutting the water off at the 'stopcock' and draining the taps will do nothing to protect the pipes from freezing inside the house. With the pressure source now removed by shutting off the stopcock there's no pressure to move the water within the pipes... opening the taps will only remove the slight amount of water within the taps fixture.
Secondly, letting a tap drizzle may not be of much value either, since, at least here in te U.S., the taps to the bath, etc., are served by to seperate pipes full of water... the hot and cold. Letting the cold water run will only provide some sourt of protection to the pipes leading to the water heater. The water coming out of the water heater to serve the house will only heat the internal water for a few feet and then gradually turn cold. Did'ja ever notice how long it takes for warm water to come out of the tap when it's first turned on?
At any rate, these are observations based on our systems here and may not be valid elsewhere...
By the way, here in the western 'Tundra" of the U.S., our service water pipes coming from our well as well as service water to our friends who live in town are buried a minimum of 6 feet and in some cases 8 feet to protect against suceeding weeks on end of -10 degrees (F)...