Believe it or not the TE's were direct decendants of the M's , the Leyland Tiger was an evoloution of the Leyland Leopard , and Metel Sections Ltd of Birmingham who supplied the frames for the M's also supplied Alexanders with the frames for the TE , both the M's and TE's shared many design features.
Way back in 1989 Bus Eireann had ambitions of having a fleet of nearly 300 TE's in service , however B.E. had a falling out with Leyland over the TE (cant recall what the issue was) and it soon became apparent that luggage was going to be a big feature of the revamped Expressway network and the TE's simply did'nt have enough luggage space , when PL 51 - 53 arrived in late 89 something along the lines of PL 61-66 was expected to become the standard long-haul coach , however a few months later PD 1 arrived and the rest as they say is history.