I fail to see why the explicit statement: "material published in 1954, and any Crown copyright material published before that date, would now be out of copyright, and may be freely reproduced throughout the world", from an official representative of the copyright holder, would not be considered permission.
I was thinking this was adressing to all material published before 1954, not only to crown copyright material published in 1954 and before.
If that's the case, I guess everything is ok then.