If you need to call one of these numbers there is a site called SAYNOTO0845 and it gives alternative numbers to ring. If you have a package with your provider these numbers are often free as they are usually normal 01,02 type ones.
The advantage of these numbers is that no matter where you ring from you only pay the cost of a local call. I used to work for an organisation which had such a number. Thee advantage of the direct number (not made available to the public) was that your call automatically went to the head of the queue and was answered immediately. However, unless you were local you would be paying long distance charges.
mike, it's been many, many years since it cost more to call a number with a different area code.
I am very much against these numbers and refuse to use them.
The website is www.saynoto0870.com
It's useful if you use a mobile or have inclusive minutes in landline package as 0870 &0845 numbers are often not included