A lovely little trug manufactured by Arnold’s of Leeds who were a school supplies company. 
This useful little tray, was probably used in an art department for brushes and paints. 
It would still be useful for exactly that or other supplies, such as cleaning stuff or tins and packets in a pantry. Alternatively. . . stand it on its end or it’s side and use it a chippy display cubby, it could even easily be adapted to hang on the wall. 
Measurements: 43.5 x 27 x 8cm deep