Seven male Conservative MPs voted against an equal pay bill on Tuesday, the only politicians to do so.
The Labour-backed Equal Pay (Transparency) Bill would require all companies with over 250 employees to publish the difference in pay between their average female employee and their average male employee, in an attempt to shine a light on the gender pay gap.
The bill, introduced by Rotherham MP Sarah Champion, passed by 258 votes to 8.
Conservative MPs were under no obligation to turn up to the vote but seven went out of their way to make an appearance, according to the opposition whips office. They were Adam Afriyie, Aidan Burley, Christopher Chope, Stewart Jackson, David Nuttall, Laurence Robertson, and John Whittingdale.
In addition, Tory MP Matthew Offord officially abstained by walking through both lobbies, ensuring his vote was counted on both sides.
7 Tory male MPs vote against #EqualPay: @AdamAfriyie @AidanBurleyMP Chope @SJacksonMP @DavidNuttallMP Laurence Robertson & J Whittingdale
Matthew Offord formally abstained by voting in both lobbies on #EqualPay
However the vote was largely symbolic, as the proposed law was introduced by the opposition as a Ten Minute Rule bill. As a result the government is highly unlikely to allow it to be debated further on the floor of the House of Commons.
The bill would enact a provision in the Equality Act which was blocked by the coalition in 2010, amid fears it would create extra bureaucracy for businesses.
Beforehand the actress Gemma Arterton and the cast of the musical Made in Dagenham protested outside parliament in support of the bill.
Analysis of official data by the Labour party suggests the average woman earns £209,976 less than the typical man over their lifetime. However the gender pay gap is lower than it has ever been before.