I guessed that the 5.45pm advertised time was to give staff 15 minutes to clear the building so the place could be all shut and locked up by 6pm.

I was wrong.

At about 5.25pm a member of staff stomped into the gallery and told us we had just five minutes left. In the next few minutes a remarkably large number of front of house staff appeared, we were hustled out, and barriers were efficiently and speedily erected all over the museum to keep us on track and stop us being distracted by the wondrous collection.

Many of the galleries were firmly shut at 5.30pm. “Oh well”, I said to my slightly disappointed wife, who had been engrossed in the elegant and expensive theatre and performance galleries, “at least we’ll have time to go to the shop.”

I was wrong again.

When we reached the shop (after having to sneak past a distracted member of staff to use the toilets), it too was firmly shut, the staff doing some light tidying and stock-checking. [...]