Yes, it sounds like the 'Surestop' remote valve in bhg's link.
It's quite a simple idea. The power of the mains pressure is simply diverted to a valve that stops flow to the flat.
When they're working properly, they do a good job. They have been known to go wrong though... with disastrous results.
Before we condemn the tap though, the symptoms don't quite add up. It should be 'all or nothing', not some taps only.
Only guessing, but I would suggest that the boiler and the basin tap are connected to the main BEFORE the Surestop valve. Which means it would have no effect on these.
In a good system, flats should have valves fitted in a 'distribution point' somewhere in the building. One valve for each flat. But that's another story.