Margaret Thatcher could have ended John Major's premiership in 1995 and possibly aborted New Labour

Sir Julian Seymour, who has died aged 80, ran Margaret Thatcher's private office from 1991 until he retired in 2001. From his obituary in the Daily Telegraph:

When John Major, exasperated at the machinations of the Eurosceptic Right, called a leadership contest in 1995, Lady Thatcher was tempted to back John Redwood. Seymour told her that for a former Tory leader to publicly back a challenger to a sitting leader would be a step too far. “I told her I always thought JR a bit odd, and an impossible bet for PM at any time,” he recalled.

He got no reaction, “other than that look when you know either that she privately agreed or was thinking about it, but was never, ever to be drawn into agreeing out loud. In summary, heart will have said Redwood, head will have said No.”

John Major later revealed that had he won two fewer votes in that leadership election (only MPs could vote in that more civilised era) he would have resigned. 

Had Lady Thatcher backed him he would have won at least two fewer votes and history might have been different. 

Who would have been his successor? John Redwood, Michael Portillo, Kenneth Clark, Michael Heseltine?

Would Great Britain have been spared Tony Blair?