Pedestrians in Wetminster, sorry, Westminster, who need to make a branch may text the word “toilet” to 80097 and get directions to the nearest public convenience for 25p.

The Register reports that the system was designed by a student named Gail Knight and is dubbed Sat Lav. It uses the phone masts closest to the desperate SMSer’s mobile phone to triangulate her approximate location.

The system is run by Westminster Council, so its emissions are less than gratifying if one attempts to get directions outside the council’s boundaries. A text from Holborn, for instance, provoked suggestions to walk to Leicester Square, Covent Garden or the Strand, missing out the public toilets at Lincoln’s Inn Fields.

No word yet if texting “lavatory” returns more upmarket results.