Had the same (or similar) earlier this week. Remarkably 1471 provided the source (normally withheld) and the number was immediately e-mailed to the Telephone Preference Service, with whom I'm registered.
After a period of at least two years with no cold calls I've had two in a week.
There's also the same philosophy with a series of letters informing you of great prizes or large sums of money that you have definitely won.
At least Royal Mail gets some reward - but such junk mail goes straight into the fortnightly waster paper recycling collection bag.