Royal Mail delivers to 29 million UK addresses; last year it generated £9 billion of revenues, of which £324 million remained as profit before tax; and it is likely to be valued at £3 billion in its privatisation share sale, indicating a price-earnings ratio modestly below ten.

Twitter — the microblogging phenomenon beloved of self-admiring celebs, but now so ubiquitous as a mode of communication that it is compulsory for British ambassadors abroad — has 200 million users and is expected to generate revenues of just £365 million this year, maybe twice that next year.