I decided to add this in response to the recent thread regarding scammers on the mailing list. You can report all types of scam to action fraud, which is part of the UK police. This website also has lots of advice to help people avoid becoming victims.
Even if you are not a victim and just hang up, you can still report it, that way I guess a bigger picture can be built as to the extent of the issue, help to build evidence too.
The Age UK website has some information internet security.
This Age UK page has some updates on the latest scams.