Time-wasting to speculate on motivation. They chose a tough woman to get the job done. Since you asked, a dissident cabinet member may have leaked the memo to push an agenda of forget the referendum, we gotta save ourselves, tear up what we did and start over again. Familiar? Consider what the paper said:
"The Treasury estimates UK GDP would be 5.4 per cent and 9.5 per cent of GDP lower after 15 years if we left EU with no successor arrangements, with a central estimate of 7.5 per cent. In headline terms, (a trade would be around a fifth lower than it otherwise would have been, (b foreign direct investment would also be a fifth lower . ."
It concluded "The net impact on public sector receipts . . .38 billion to 66 billion annually because of a smaller economy." Enough to give anyone the heebie-jeebies. I believe it's a sober estimate because Treasury wouldn't have made it without consulting Governor of the Bank of England Mark Carney, a Canadian previously Governor of Bank of Canada, first and only non-Brit to hold the job in 400 years.
(Canada survived The Great Recession in better shape than any of the G20 because of regulations.)
