Post by occamIt is funny how some standard expressions strike you as odd at times,
when the ear catches them at just the right moment.
"...not by a country mile" has of course nothing to do with kilometres.
It just means "... by far" or " ... by a large margin".
I am not sure however why a country mile should be any longer than a
town mile?
I think the idea is that country dwellers when asked by strangers for
the distance between two places will give a small number than the actual
distance.
OED:
country mile n. colloquial †the distance customarily thought of as
a mile in (a particular part of) the countryside, and typically
regarded as longer than a standard mile (obsolete); (hence,
frequently in figurative contexts) a long distance, a long margin;
cf. Irish mile n. at Irish adj. and n. Compounds 3.
Irish mile n. the customary length of a mile in Ireland, 2240 yards
(approx. 2048 metres) (see mile n.1 1a) (now historical); (now
chiefly colloquial) a long distance; an indeterminate or unfixed
distance; cf. country mile n. at country n. and adj. Compounds 4.
The standard mile is 1760 yards (approx. 1609 metres).
The OED comments:
The length of the mile has varied considerably at different periods
and in different localities, chiefly owing to the influence of the
agricultural system of measures with which the mile has been brought
into relation (see furlong n.). It was fixed by statute at 1760
yards (viz. 8 furlongs of 40 poles, each pole being 16½ feet) in
1592 (Act 35 Eliz. I, c. 6, s. 8), and in Britain is also called a
statute mile. This is also the legal mile in the United States. The
obsolete Irish mile was 2240 yards (approx. 2048 metres), and the
Scottish mile (obsolete by the late 19th century) was 1976 yards
(approx. 1807 metres) although values probably varied according to
time and place.
--
Peter Duncanson, UK
(in alt.usage.english)