Wigan UK now, I don't take calls that I don't know, so I let it ring until it went to voicemail but they didn't leave a message. I tried to call the number back before I googles the number, but got a message from Telecom saying the number was not recognised.
Having got to this page I'm obviously better informed, but that obiously won't stop these people.
Got the call at 18.43 - Malvern, Worcestershire - had recently subscribed to a number of sites to do on-line surveys and was worried it might be connected - appears not according to these posts - unless anyone out there knows anything different. Already on TPS register so they're obviously not checking that.