do out of date tax discs pose a security threat to either the vehicle or owner

would a so called collector of tax discs be able to do anything naughty or dangerous or malicious with out of date tax discs?????

nothing more than they could do by reading your tax disc through your window i suppose

A tax disc is only worth something when it is within date. When it expires it is useless.

He could use them to fake labels for Guiness bottles