Same sex partners of Eurotunnel workers will from today be entitled to the same concessionary travel as heterosexual partners.
Until now only staff and their spouses or common-law partners have been able to make use of the £1 cost for a single crossing between Folkestone and Calais.
The Transport and General Workers' Union, who represent 1,300 staff at Eurotunnel, negotiated the equal rights.
Couples need to have lived together for three years and to have signed an affidavit to confirm their partner status in order to qualify for travel concessions.
Graham Murfet, T&G regional officer, said, "This agreement is a victory for equal rights and represents the success of a partnership approach with a progressive thinking company. Our T&G reps were the first to raise this issue and have seen the negotiations through the finer detail and into practice."