"intent to defraud" would be very difficult to defend yourself against. Publishing the means by which others could commit fraud might be classed as "incitement". I'd say Tesco's lawyers are about to have a little fun.
A howto is not incitement. If I tell you how to tie a noose I'm not inciting you to commit suicide, nor even to tie a noose. Very expensive barristers can probably twist a situation sufficiently to get an incitement charge though.
