Following your reference, Mark, I have sent an e-mail about our postcode which leads people astray. I now have found the correct co-ordinates in degrees and minutes:
Postcode: SL0 9LB
Lat.:51deg. 31' 32.8074" Long.:0deg. 30' 20.88"
decimal: 51.5257801/-0.50580024
The postcode covers 4 properties, all on Swan Road and only accessible thereby. Currently SATNAV sends parties to Coppins Lane, which is nearby, but inaccurate and inconvenient.