Most notably his sister Elsie Duval, who was the second person to be released under the Prisoners (Temporary Discharge for Ill Health) Act 1913 (the so-called "Cat and Mouse law"),[3] and was married to fellow suffrage campaigner Hugh Franklin.

The MPU was non-partisan and welcomed members who shared its core values to "obtain for women the parliamentary vote on the same terms as it is or may be granted to males" regardless of their political beliefs.

In July 1909, Duval was charged with “Aiding and abetting Marion Wallace Dunlop, in wilful and malicious damage to the stone work of St. Stephen’s Hall, House of Commons, by stamping it with an indelible rubber stamp, to the value of ten shillings.

[2] Before she married Duval in 1912, Suffragette Una Dugdale (1885–1945) caused a national uproar (1885–1945) by announcing she wouldn't include the term "obey" in her wedding vows, but she changed her mind after learning this could cast doubt on the legality of the marriage.

Dame Christabel Pankhurst, Lady Constance Lytton, and the Pethick-Lawrences wore WSPU colours at the wedding.