Royal Mail

Royal Mail was the name of a British postal company. (TV: Day One)

The TARDIS narrowly missed crashing in to one of the company's vans. (TV: The Christmas Invasion)

One of their workers was nearly murdered by the Sex Gas in the host body of Carys Fletcher. (TV: Day One)

Another postman heard Owen Harper being shouted at by Ed Morgan. (TV: Ghost Machine)

A Royal Mail card was stolen by the staff of Torchwood Three. (TV: Children of Earth: Day Three)

One of the storage bags was seen on the Thames House helipad. (TV: Children of Earth: Day Five)

Behind the scenes
In the real world, Royal Mail published the Doctor Who 50th Anniversary Royal Mail Prestige Stamp Book, a stamp book which included the Eleventh Doctor comic story Doctor Who and the Last Stand.