 The peerage was created in 1857 for the Whig politician Lord Robert Grosvenor.He was the third son of Robert Grosvenor, 1st Marquess of Westminster and his wife Lady Eleanor, daughter of Thomas Egerton, 1st Earl of Wilton.Both Lord Robert and his elder brother Lord Thomas were in special remainder to the Viscountcy of Grey de Wilton and Earldom of Wilton created for their maternal grandfather in 1801, and on the latter's death in 1814 Lord Thomas succeeded as second Earl of Wilton.