As PF says -
IEA was totally separate, Aspro Holidays (owned by a Greek Cypriot family - Asprou) was started from a corner grocer's shop in Cardiff and, as already mentioned, developed their in-house airline IEA in 1987, a single B737-200 for a summer only 1987 before going 2 x B737-300 for 1988 and it went from there - with 737-400, 757-200 and A320.
We handled them at LGW - great outfit and lovely crews - Often went down route with them for the day out in case of any issues that may come up to lend a hand.
Airtours International bought Aspro Hols and IEA morphed into AIH.