The following (updated) extract from the message board, describes the Radar disabled toilet scheme:
radar – 6,500 locked public toilets
Here are the details of the Radar scheme. There are 6,500 toilets in the UK that are part of this scheme. The toilets are owned by the provider, not RADAR. RADAR just provides the key service, to stop vandalism. They would like all toilets unlocked if possible.
I have seen these toilets in Motorway service stations and shopping centers.
12 City Forum
250 City Road
Tel 020 7250 3222
to get a key do the following:
Go to the RADAR bookshop by clicking HERE.
First item links to the NKS Key (to buy). There are two prices. With a declaration no VAT is charged (e.g. "I am a disabled person and I wish to buy a national key scheme key") – the price is £3.50. Without a declaration the price is £4.11 inc VAT.
Second item links to the NKS Guide 2005 - Accessible Toilets For Disabled People). The price is currently £10.00 (for UK delivery).