<As a Feb 1980 it is a 1979 "model" year bike HA 11001 being the first that year,>

A T140 built in Feb. 1980 it would certainly be a 1980 model year bike.

HA11001 was indeed the first 1979 "year" E model but HA corresponds to a build date of July 1978.
1980 year model production commenced at PB25001. PB being the date code for a 1980 model built in November 1979.