It is very important that...

[cannonkuo]

It was very important that Britain did not relax its present tough position while attempts were made to find a diplomatic solution.
(Falklands: No.10 record of conversation (0830-1000Z) (MT-Haig) [first meeting: discussion of Haig proposals] [declassified 2012] | Margaret Thatcher Foundation)

As I have learned, the sentence pattern "It is important that S. (should) V..."
Can the sentence be rewritten like this: It was very important that Britain not relax its...without changing the meaning?

 

[Rover_KE]

Maybe, but it’s the subjunctive mood which few speakers of British English use or even understand.

I’d leave ‘did’ in if I were you.