The "£3.00 to vote" scheme was clearly absurd; however, as I understand it, part of the signing-up process involved stating that you "support the Labour party". Consequently, anyone who did sign up, despite being anti-Labour, is by definition a self-confessed liar.
Indeed, if I were ever for personal gain to 'add my signature' to a document I knew to be false, I would consider myself to be a perjurer. (Personal gain can mean political as well as financial advantage. Sadly, however, any sense of honour is largely a thing of the past.)