Playing rugby at school (St Patrick's, Silverstream, Upper Hutt) and with Upper Hutt RFC, Cowan started 2004 – the year after he left school – playing football with the Stokes Valley under-21s in Lower Hutt and then briefly with the Upper Hutt 21s, before moving to Australia for a year at the end of the pre-season.
He rejoined Upper Hutt RFC at the start of 2005, becoming part of the premier squad, winning the Swindale Shield and making the Jubilee Cup semi-finals in his first year in the team.
He joined the Wellington Rugby Academy in 2006 and played for Wellington at under-19 and under-21 levels and Wellington 'B'.
He moved to Cornish Pirates in 2009, making 29 appearances for the side and scoring 26 tries, then to Worcester in January 2012 before signing for London Irish this season. In his first four games for the club, he scored two tries.
He is a cousin of Western Force prop Pekahou Cowan who has won five caps for the Wallabies (most recently against South Africa in 2011).
He qualifies to play for Scotland through his mum, Joan, who was born in Dunoon – and who recently completed Ironman New Zealand.
Of his decision to opt for Scotland he says: “The Scottish side has always been a strong part of my family, my career really kicked off in Great Britain and Scotland’s always been the country, in my mind, that I wanted to represent.”