Now, the details around this one are more than a little hazy (pun intended), but given the photographic evidence, we're going to say that it's pretty likely that the rumors are true, at least in part. The rumor was denied by George Harrison years later, but why would John Lennon Lie? (John Lennon was always our favorite.)
Whilst it can't be proven that they blazed up within the walls of Buckingham palace or just enjoyed a sneaky one on the way down to meet the queen, they definitely look as high as kites in the photos that have been in circulation since they met her majesty, the queen of England. More power to them we say, plus, surely, they're not the first high people the queen has encountered?