It works on any cheque that you write, it doesn't matter whether it is to an individual or a shop.
The cheque card details written on the back of the cheque are what identifies it as been guaranteed! The recipient of the cheque must record the card number etc, if you write the details on the cheque yourself, it invalidates the guarantee.
koster - I used to work in a bank and believe me you can usually tell when someone writes their own cheque guarantee details on the back of a cheque - even when they try to disguise it!
Agree with Spudqueen, I also worked in a bank for 20 years and you can definately tell when the writer of the cheque has written their own number on! They are usually stupid enough to do it in the same pen and handwriting!
I doubt a bank would ever send a cheque for handwriting analysis, they would just return the cheque unpaid. The payee wouldn't query it as they would know that the drawer of the cheque had written the card number on themselves.