broadwood & sons square piano

[Gill the Piano]

Carefully! If I remember rightly, the boards behind the keyboard slide upwards to leave the action exposed so you can slide it out towards you, gently! Look at each end of the various boards for swivel pegs which you turn to help release the board/rail. On early uprights there was sometimes a wooden protruberance (I know, but I can't think of a better name for it) on some rails which you slide in the direction of the middle of the keyboard (ie, left one goes to the right and vice versa)to allow the rail to be removed. I believe this was also done in some squares.
I do hope this makes sense; if not, I expect a grownup will be along in a minute to correct me!