Weaponsight Image Intensified L5A1

[MSnafu]

They certainly had a variety of options for the sight, but Delft were a heavy supplier to UK MOD through EEV.
This is the UK company Starlight Nightvision Ltd who will be able to help you source the right tube:

Starlight Night Vision. Information on Longbow, Kite, Archer, image intensifier tubes (2nd and 3rd gen), night vision rifle scopes

Thanks. Already sort of in contact with them.