Well before Mrs Thatchers time,and doubt she would have offered any help to the industry if she had..
getting back to the re-engining idea, the Chinese -who by the late 70s early 80s had the most Tridents in service did look at re engining with two Jt8d's they were going to remove the centre engine and reinforce the area vacated,they were granted an export licence and actually bought 2 engines but nothing seems to have come of it,the cost of re-engining just dosnt stack up unless you can do on a large scale and sell on to others to recoup some of your costs.This is what happened to the 1-11,no reason that the conversion couldnt be done and was flown and tested,might even still be one flying around in the U.S. with Tays on and a glass cockpit,but not enough airframes to sell it too unfortunatly..