British East Africa. (Kenya). 1942. Official Bank mail with (oval cachet on reverse) stamp-less addressed to London cancelled by 'Postage Paid/ 20 Cents/ Eldoret' in red dated '24th Sep 42'.
Proud 'The Postal History of Kenya' notes he has only seen examples set with '10 cents' and '15 cents' dated (5.1.54) - (9.9.59).
This Eldoret '20 cents' in red is 12 years earlier than the Ted Proud listing.