[4] Thomas was the son of Sir George Manners, 11th Baron de Ros (c. 1470 – 1513) by his wife Anne St Leger (1476–1526).
In January 1522 he was made steward of Pickering, Yorkshire, and from April to October of the same year he held the appointment of Lord Warden of the East Marches, in which he was succeeded by Henry Percy, 6th Earl of Northumberland.
He was appointed a Knight of the Garter on 24 April 1525 and on 18 June 1525 he was made Earl of Rutland, a title previously held by members of the house of York.
[6] He was a great favourite of King Henry VIII and received many grants, including the keepership of Enfield Chase on 12 July 1526, and Belvoir Castle, which remains the chief seat of his family.
He held a joint command with the Earls of Huntingdon and Shrewsbury and marched to Nottingham and thence to Newark, Southwell, and Doncaster against the northern rebels.
His Garter stall plate of brass inlaid with coloured enamel, survives in St George's Chapel, Windsor Castle.
His head wears a basic form of coronet and rests on his tilt-heaume on top of which is the Manners crest of a peacock in pride on a Cap of Maintenance.
The effigy of the countess is dressed in a gown and a short cape and wears an ermine-trimmed mantle fastened by a cordon whose ends reach almost to her feet, under which is a griffon.
The base of the tomb is decorated with corner pilasters, tasselled swags and "weeper" figures representing knights, ladies and others.