Update: 11:30 GMT Thanks to Bugsy for the following
Update: 11:10 For those wanting to try this number from outside the UK you need to dial the following
From non-UK dial: +44 207 946 0893
From the UK dial: 020 7946 0893
It seems like Penny's Phone Number from the clue hunt is a dummy number setup for the game. Numbers have played key parts to the game, could they mean something else...?? Another coordinate or just another number??
Once again thanks to everyone that sent this info in....including Elpaw and MD for the heads up.
The phone number you get when entering the codeword is fake, the UK equivalent of 555 in the US. The numbers 020 7946 0000 to 020 7946 0999 are assigned for Drama purposes.