Our site team fitted extra metal piping to the bottom of one desk to raise its height.

Ikea make a good height adjustable table which, while not a standard eam desk, is very versatile for use with a range of pupils.  https://www.ikea.com/gb/en/products/desks/desk-computer-desks/skarsta-desk-sit-stand-white-spr-29084966/

Depending on the type of legs the exam desks have, could you use a set of table raisers, e.g., Leg X as it's just for a limited amount of use?

Many thanks for you suggestions.

I passed on the options to the school and they have decided to purchase the Alderton’ cut-out table from James Spencer.

Thanks again

Gemma