European Union Bill

My Lords, I would like to spend a little time ruminating on something that the Minister said. He said that if this Parliament repealed the 1972 Act and the relevant parts of the other Acts that he mentioned, we would still be bound by Article 50 of the Lisbon treaty. Article 50 is of course the laborious and expensive process that Lisbon allows for a member state to leave the European Union over a period of some two years. Why is that so? Surely if we have repealed the 1972 Act, have we not repealed everything that flows from it, including Article 50. Could we not then get out much quicker and rather more cheaply?