The GMB has won the right to negotiate pay and conditions for a group of water workers in Nottingham.
Union recognition was achieved after a ballot of employees at Severn Trent's site in Haydn Road.
Twenty-seven of the 53 employees voted for the GMB to represent them - with eight against.
The result satisfied the two tests laid down in the statutory recognition laws introduced by Labour in 2000.
A simple majority supported recognition - and it was more than 40 percent of the total bargaining unit.
The vote was organised by the Central Arbitration Committee (CAC) - the quango that adjudicates recognition claims.
The workers to be represented are described as "all employees including managers, other than the general manager, at the Severn Trent Utility Services Limited, Haydn Road site".
The ballot was required because just under half of the bargaining unit where union members.
The GMB was formerly the General, Municiple, and Boilermakers union.
There is a report of this case on the CAC website.
Since July 19 this year eight recognition applications have been submitted to the CAC. Six of them have been from the GMB.
While the trade union movement generally has slowed the pace of new workplace organisation the GMB must be praised for committing resources to making life better for potential members with hostile employers.