OK I will try and join in...here are my "small 3":
Hornby type 20 1954-1968 Loco 5" long w/o tender - clockwork Side note : This engine and matching freight wagons was just about the last new trains that Hornby offered in 0 gauge, they moved completely to 00 after about 1968.
French Hornby M0 series 1950-51 loco about 4" long w/o tender - clockwork
A Karl Bub postwar clockwork- date unknown to me, likely 1960's Loco about 4" long.