Interesting, welcome to the Forum! What was their fate?

W&R 15 lists the Cumbernauld Defins as ’06’, ’09’, ’18’, ’37’, ’40’ & ’51’ (all ‘red’).

W&R 16 has ’06’, ’09’, ’37’ & ’40’ as shipped to the USA.

It would appear ’51’ is still here with us which leaves ’18’ unaccounted for.