 The amended Parliament Act was never used in the 1940s or 1950s, possibly because the mere threat of it was enough.The Salisbury convention that the Lords would not block government bills that were mentioned in the government's manifesto dates from this time.Salisbury believed that since, in being returned to power, the Government was given a clear mandate for the policies proposed in its manifesto, it would be improper for the Lords to frustrate such legislation.