Postcode
From Tardis Wiki, the free Doctor Who reference
As noted by Bill Potts, postcodes could be used to find houses. (TV: Knock Knock)
Coal Hill School's postcode was E2 7QE. (TV: Nightvisiting)
1 Wellington Road's postcode was N1 0HR. (TV: Co-Owner of a Lonely Heart)
Minto Road was located in the W11 postcode district. (TV: The Church on Ruby Road [+]Loading...["The Church on Ruby Road (TV story)"])