Harry Goodman Intsaun and AE Boss, did a good deal (£££) with BA for buying new 757's by taking some of BA's large 757 order (-236's) as long as AE did not change the interior specs at Boeing, thus HG got the new planes for AE at the discounted price that BA was paying for them.
AE also leased from BA a brand new BA liveried 757 G-BIKF for summer 1983, and during the winters BA took some of AE's 757 for LHR shuttle ops.
All very cosy.
All AE 757 orders for AE/Air Europa SA were 757-236, with 535C, then after with 535E4 engines.
AE never had any 757-2S3 orders.
S3 was AE own code for new 737-200/300/400 orders
Q8 was ILFC for AE Italy Spa for new 767-300 & 777 orders
T7 was Monarch's own customer order code.
(Y0 was GPA, 3A was AWAS, K9 was Bavaria Flug -- all for new Boeing a/c on Monarch leases)