A graduate of the Glamorgan Academy, Michael O'Shea impressed with the bat as a youngster and was a frequent tourist with England's Under-19 side, touring India with them in 2004-05 and Bangladesh in 2005-06. His promise was recognised with an NBC Denis Compton Award in 2005, and in the same year he made his first-class debut for Glamorgan against Bangladesh A aged 17 years and 325 days.

The transition from youth to first-class cricket was not easy for O'Shea, and his figures suggest he is more at home in limited-overs cricket. He still had not secured a spot in the first XI when, in June 2009, he was suspended for three weeks by the county after being caught drink-driving. A repentant O'Shea returned to Glamorgan service in Twenty20 cricket, but enjoyed limited success and soon found himself back in the Second XI.

In 2010 he played for the Unicorns in the Clydesdale Bank 40, contributing a couple of quick 30s and 40s and hitting a rapid half-century against Surrey, before returning to Glamorgan's Seconds. He remained there in 2011, and as well as batting in the top order also found his medium-pace seamers called upon more often.
Liam Brickhill June 2011