The police were investigating Banksy’s stunt:

“We’ve received a number of complaints about an offer of a free Banksy print to people living in six Bristol constituencies in exchange for them voting in a certain way in the forthcoming election and we can confirm we’re investigating the offer. It is a criminal offence under the Representation of the People Act 1983 for any voter to accept or agree to accept a gift or similar in return for voting or refraining from voting. Any person participating in an offer to receive a gift is at risk of being prosecuted.”

Still, now he’ll be able to flog them at higher prices now they are contraband. Good capitalist that he is…