Lt. Col or Full Col, I think the corps, regiment, unit and years of service are more important as Melchett01 indicates.
500N - as long as he remembers that whilst some Regiments are better than others, all Regiments are acceptable where as Corps are most definitely not! Nothing more embarrassing than asking a chap about his war record only to find he served in the Women's Auxilliary Balloon Corps.
And the 1* was fine ..... Mrs 1* on the other hand wasn't quite as
impressed
O-D - so just how does one use RAF ranks in a social setting? Unlike our sister services whose ranks can be abridged to one word - Colonel, General, Commander, Admiral etc, RAF ranks are a bit of a mouthful. I for one would find it a little tongue-tyign constantly refering to your host as Gp Capt, Wg Cdr etc.