White-collar professionals are now more likely to join a union than those who may be more in need, such as low-paid workers, according to the Labour Force Survey.
Findings also show that in 1995, more than 35 per cent of men and fewer than 30 per cent of women were trade union members. But today, the gap between men and women is just 0.1 per cent.
The biggest differentiating factor in trade union membership remains the geographical divide. Figures range from 21.8 per cent in the South East and 26 per cent in the South West, to 38.3 per cent in Wales and the North East of England, and 34.9 per cent in Northern Ireland.
Age also plays a role, with just 10.6 per cent of those under 24 being trade union members, compared with 35.5 per cent of people aged over 35.
Despite falling membership, union members have consistently earned more than their non-union counterparts.