Lambert Simnel was born around 1477. His real name is not known - contemporary records call him John, not Lambert, and even his surname is suspect. Different sources have different claims of his parentage, from a baker and tradesman to organ builder. Most definitely, he was of humble origin. At the age of about ten, he was taken as a pupil by an Oxford-trained priest named Roger Simon (or Richard Symonds) who apparently decided to become a kingmaker. He tutored the boy in courtly manners and contemporaries described the boy as handsome. He was taught the necessary etiquettes and was educated well by Symonds. One contemporary described him as "a boy so learned, that, had he ruled, he would have as a learned man."
Simon detected a striking resemblance between Lambert and the supposedly murdered sons of Edward IV, so originally intended to present Simnel as Richard, Duke of York, son of King Edward IV, the younger of the vanished Princes in the Tower. However, when he heard rumours that the Earl of Warwick had died during his imprisonment in the Tower of London, he changed his mind. The real Warwick was a boy of about the same age. He had a genuine claim to the throne as the son of the Duke of Clarence, King Edward IV's brother.
When Henry VII heard about this, he knew that the real Warwick was still imprisoned in the Tower. On 2 February 1487 he presented Warwick in public to show that the young pretender was an impostor. The King also declared a general pardon of all offences, including treason against himself, on the condition that offenders submit to him.
The Earl of Lincoln, formerly the designated successor of the late King Richard III, joined the conspiracy against Henry VII. He fled to Burgundy, where Warwick's aunt Margaret of York, the Dowager Duchess of Burgundy, kept her court. Lincoln claimed that he had taken part in young Warwick's supposed escape. He also met Viscount Lovell, who had supported a failed Yorkist uprising in 1486 (see Stafford and Lovell Rebellion). Margaret collected 2,000 Flemish mercenaries and shipped them to Ireland under the command of Martin Schwarz, a noted military leader of the time. They arrived in Ireland on 5 May. King Henry was informed of this and began to gather troops.
Simnel's army — mainly Flemish and Irish troops — landed on Piel Island in the Furness area of Lancashire on 5 June 1487 and were joined by some English supporters. However, most local nobles, with the exception of Sir Thomas Broughton , did not join them. They clashed with the King's army on 16 June at the Battle of Stoke Field and were defeated. Kildare was captured, and Lincoln and Sir Thomas Broughton were killed. Lovell went missing; there were rumours that he had escaped and hidden to avoid retribution. Simon avoided execution due to his priestly status but was imprisoned for life.
King Henry pardoned young Simnel (probably because he had mostly been a puppet in the hands of adults) and gave him a job in the royal kitchen as a spit-turner. When he grew older, he became a falconer. He died around 1525.
A popular legend attributes the invention of the Simnel cake to Lambert Simnel, although this is undoubtedly false, since the Simnel cake appears in English literature prior to Lambert's escapades.