"The Townshend peerage case was one where marquis Townshend (then called Lord Chartley) married Sarah Dunn Gardner in 1807; a year later she left her husband, sued in Ecclesiastical court to have the marriage annulled because of his impotence but dropped the suit and eloped with a brewer of St. Ives. Their children initially bore the brewer's name (Margetts) but from 1823 took the name Townshend, and one took the style of Earl of Leicester. The marquis took no steps to dissolve the marriage, and his brother had no means to dispute the legitimacy of the so-called Earl of Leicester, because no property depended on the title. As time went by and witnesses died off, it seemed the imposture might not be preventable. So the brother and heir presumptive petitioned the house of Lords for inquiry respecting the descent of these honours in May 1842. The next year the marquis himself also petitioned the House.

Ultimately a private bill was brought "to declare the illegitimacy of certain persons alleged or claiming to be children of the Most Honourable George Ferrars, Marquis Townshend". There was much debate (how could you bastardize the children of a valid and continuing marriage? Was the royal prerogative not infringed? What about ordinary courts?). In the end the bill received royal assent on July 12, 1843 entitled "An Act to declare that certain persons therein mentioned are not children of the Most Honourable George Ferrars, Marquis Townshend" (6 & 7 Vict c. 35) and declaring that "the said several children of the said Sarah Gardner, Marchioness Townshend, hereinbefore respectively mentioned, are not nor were, nor shall they or any of them, be taken to be or be deemed the lawful issue of the said George Ferrars Marquis Townshend" (one child, having no legal guardian, was excepted from the provisions). (Based on Frederick Clifford, ''A History of Private Bill Legislation'', 1885, vol. 1 p. 443–450)."