Subsequently, he sat for Colchester, 1850–57; for North Leicestershire, 1857–85; and for Melton from 1885 until, in 1888, he took his seat in the House of Lords upon succeeding to the dukedom.

[5] In the early 1840s, Manners was a leading figure in the Young England movement, led by Benjamin Disraeli.

Manners made an extensive tour of inspection in the industrial parts of northern England, in the course of which he and his friend George Smythe, later 7th Viscount Strangford, gave well-received speeches.

In 1843 he supported Lord Grey's motion for an inquiry into the condition of England, the serious disaffection of the working classes of the north being a subject to which he was constantly drawing the attention of parliament.

Among other measures that he urged were the disestablishment of the Irish Church, the modification of the Statutes of Mortmain, and the resumption of regular diplomatic relations with the Vatican.

[5][6] In 1844 Lord John vigorously supported the Factories Act ("Ten-hours Bill"), which, though strongly opposed by Manchester representatives, was ultimately passed in May 1847.

A few days later, he and his friends attended a festival at Bingley, in Yorkshire, to celebrate the allotment of land for gardens to working men, a step which, through the agency of his father, he had done a great deal to further.

They had two children: His wife died 7 April 1854, aged 23, from childbirth complications, weeks after giving birth to a daughter, Edith, who lived only 12 days.