I need to lift (but not keep) half a floor comprising of 7.5"x1.25"
boards.
the boards are not T&G but square edged with a 1" wide metal strip acting
as
a tongue between them.

Interesting coincidence. I discovered I had some of these yesterday.

In my case I found that the metal tongue could be pulled out from the end of
the boards... Don't know if this helps.

Colin