Well the original question made sense, anyway!
http://www.theanswerb...w/Question995003.html
It's actually fairly common practice for potential employers to seek information from people who work at the same level, or who are junior to, the person being considered for the job. In my opinion it's an excellent idea, since it tends to find out the real truth about people!
However it's unusual for it to be done in writing. It's usually done with a series of discrete phone calls. (When I was teaching, it happened all of the time. We'd get a job application from someone who was teaching in another school in the city, and staff would quietly be asked to 'put out feelers' to find out everything that was known about the candidate).
Putting anything into writing is always rather risky, irrespective of whether it's a 'formal' reference or not. The candidate has no right, under the Data Protection Act, to receive a copy of the reference from the person who wrote it. However he normally does have the right to demand that the recipient releases a copy of the reference to him. (So the 'disclaimer', referred to in your other post, has no legal standing).
Chris