Edward Poynings was born in 1459 into a family with a tradition of turning against its Yorkist Kings: his father had been a sword-bearer to Jack Cade during his rising in Kent. Edward himself took part in a rising against Richard III in 1483 - his rising in Kent was planned to distract the King while the Duke of Buckingham did the work.
After the failure of the rising, Edward was forced to flee to the Continent after Richard read his name in a proclamation. Hardly surprisingly, he chose to flee to the court of Henry Tudor, who was lying in France waiting to strike a fatal blow to the rotten heart of Richard's government. After the Battle of Bosworth, in which Henry won the crown from Richard, ending the War of the Roses, Edward was made a knight and sworn into the Privy Council (the highest Council in the land). Henry was not known for his zeal in handing out patronage, and so it is likely that he felt Poynings was a valuable ally.
His years in Ireland
Sir Poynings' most famous years were the ones he spent in Ireland. Ireland was a traditional Yorkist stronghold, and a possible place where rebels to the new King's rule could hide out. Although the Battle of Stoke in 1487 was the last Henry had to fight against his own subjects, there was always the chance that the Earl of Kildare (who ruled Ireland de facto) would antagonize matters and maybe help rebels field an army against the King. Indeed, in the 1487 battle, Irish troops had fought against the English crown. Although the battle frenzy of the half-naked "Wild Irish" alienated Englishmen from joining their side, they were a force to be reckoned with.
In 1491, when Perkin Warbeck arrived in Ireland looking for Irish support, the Earl of Kildare decided not to get involved this time - Henry had only been lenient to him after Stoke because he had a weak grip on the English crown and could not be hassled with this remote colony. However, this time, Kildare's lack of action was enough to implicate him - after he failed to exert himself to put down Warbeck and Henry was forced to send an army himself to do it, he was dismissed from office by Henry. Henry tried to get two local magnates to rule, but this attempt was disastrous, and when it was revealed Warbeck planned to return to Ireland, Sir Edward Poynings was sent in (it was 1494 by this point).
Sir Poynings was appointed Deputy, with Henry VII's son Henry (later Henry VIII) as viceroy. Sir Poynings arrived with 1000 men and set about crushing Irish resistance and filling offices with Englishmen. The Earl of Kildare was arrested on an obscure charge of treason in Ulster and sent to the Tower of London. But Sir Poynings most remarkable action was the calling of one of the most famous parliament's in Irish history: the Parliament of Drogheda. On December 1, 1494, Poynings passed numerous laws which ate away at Irish autonomy: they could no longer pass a law without the King of England approving it, no parliament could be called without likewise approval, and marriage between English colonialists and the Irish was forbidden. This was known as Poynings' Law and was lamented by the Irish until the twentieth century.
However, despite Sir Poynings' successes in defeating the Irish and ensuring Yorkist rebels would no longer find sanctuary in Ireland, Henry eventually realized that no Englishmen could achieve as much there as a local noble. He decided that
"If all of Ireland cannot rule the Earl of Kildare, he is fit to rule all of Ireland."
Sir Poynings returned to England in December 1495, leaving a colony with much more centralized Crown control. The Earl of Kildare was henceforth entirely loyal to the Crown, and the English could extract moneys from it with greater ease. When Henry died in 1509 there was no 'Irish problem.'
Outside of Ireland
Apart from these years in Ireland and before his death in 1521, Sir Poynings achieved various other accolades and helped in other aspects of government. He escorted Catherine of Aragon to London in 1501, was ambassador to the Pope in 1515 and took part in negotiations between Henry VIII and Francis I at the Field of the Cloth of Gold.
Henry VII did not often elevate men to the peerage, and Sir Poynings received no such accolade. Rather, he was made a Knight of the Order of the Garter in 1491 (37 men received this reward during Henry's reign.) This is typical of how Henry rewarded men that had been loyal to him, especially before Bosworth - a less prudent King might have been quick to have raised his allies into the peerage, but Henry preferred to limit the number of magnates and hence face less chance of rebellion from over-powerful Lords. Sir Poynings was one of an emerging breed of gentry with real influence and power - power which before had rested with the nobility, but was being stripped away from them.
Sir Poynings died at Kent in 1521. Henry VIII had likewise not raised him into the nobility.
The Tudor Years, Edited by John Lotherington (Hodder & Stoughton, 1994)
England and Wales under the Tudors by Sinclair Atkins (Hodder & Stoughton, 1975)
Henry VII by Caroline Rogers (Hodder & Stoughton, 1991)
Government and Community: England 1450-1509 by J. R. Lander (Edward Arnold, 1980)