Is Piers Morgan a liar or are his diaries unreliable evidence?

“Tea with Tony Blair at No. 10. He was yawning a lot and drinking endless cups of tea. I tried to wake him up a bit.”

Piers Morgan's diary entry for 26 March 1997, taken from his 2005 book The Insider: The Private Diaries of a Scandalous Decade.

I presume that most people would remember that the 1997 General Election was not held until 1 May 1997, so on 26 March did Piers Morgan have tea with John Major but thought it was Tony Blair, have tea with Tony Blair but at another location and thought Number 10 would sound better or did he just make it up?

During the Leveson Inquiry Piers Morgan was asked if his diaries, of his decade up to 2004 as editor of both The Mirror and the News of the World were reliable, he replied "Well, that’s a moot point" Indeed it is Piers, indeed it is.