10
93*. Second, there is a significant but unknown degree of dual membership; mobile workers may belong to two or three unions in differen trades (this is perhaps particularly true of seamen, a very large pro-
portion of registered seafarers in fact working mainly in land
occupations, but keeping their seaman's book and union card as an
insurance).
Particularly, in industries where both left-wing and right-
wing unions are important, some workers belong to both. Union officials
in some trades involved have put the proportion of their members in this
position at between 5% and 10%. So that, in all, effective union
membership is significantly lower than the nominal figures suggest.
15.
Union membership density appears highest in utilities, water
and land transport, low in private commerce and service occupations
(where there are in any case many self-employed**), and lowest in
construction and manufacturing (apart from a modest concentration in
textiles and certain long-established craft trades). Although about half
the industrial labour force consists of women, only about 60,000 are
union members, although (in nominal terms, at least) female union
membership appears to be rising faster than that of men.
.....
In earlier years, claimed membership generally tended to exceed paid-up membership considerably. 1970 appears to have been the year when the Registrar of Trade Unions achieved most success in relating claims to reality.
** Some unions apparently accept these as members, since workers will
move between paid work and self-employment. There is indeed, a small number of "mixed" organisations of workers and employers (not included in the figures above), though their total membership is only between 5000 and 6000.