Digit C cannot be greater than 2, because then a minimum sum - such as 31 x 425 - would produce a five-digit answer. This knowledge, combined with the known XXX XXX shape of the interior workings, makes it very likely that CD is 12. This is indeed the case, and the complete sum is:
483 x 12 = 5796
Ivor Smith will receive £20 for this contribution.