The size 8 and 9 wewre the largest two sizes made. With the jacket 8090 means for height 180 to 190cm with a 1020 or 100 to 120 cm chest. Size 1 2 and 3 (6070) was for some one 160 to 170 cm tall. Size 4, 5 and 6 (7080) was for 170 to 180 cm tall. Each of the heigh ranges had three chest sizes, usually 8595 for 85 to 95cm chest, 9505 for 95 to 105cm chest and 0515 for 105 to 115cm chest. I have no idea how the trouser sizes work, except that sizes 1 to 3 were for a 29 inside leg, 4, 5 and 6 were for a 32 inside leg and 7, 8 and 9 were for seriously tall blokes who inhabited the regions where the air is thinner.
Most servicemen find that when they try their old kit on again after 5 years out of the mob, their old uniforms have mysteriously shrunk whilst in the cupboard.........