advice needed on how to stop a person who i know is doing this and in receipt of benefit, yet using another name on his registration documents etc.  how do i find out if this name is an alias (i.e. inland revenue, electoral etc) and what steps do i follow (legally) to put a stop to this despicable person

you could try getting in touch with your local dss office,and the kennel club.

It might not well be a alias but a another member of the family.  In which case assuming they are a non tax payer and not going above the taxable income bracket then I dont think there would be much that can be done except they will need to declare it.  The only thing you can do is report it to the DSS as I believe they have a fraud line but I dont see what you personally can do legally.  If he is clever enough to put the dog into someone elses name then I am sure he is sharp enough to have worked this out.