Instead, with the Blues' season all but over ahead of next week's final-round clash against league leaders Queensland, Cowan decided it was time to pull the pin on a stellar career which generated 10,097 first-class runs and 18 Tests for Australia.

Shocked NSW officials only received the news late on Tuesday afternoon following the 23-run loss to defending Shield champions Victoria, a decision the 35-year-old Cowan had been mulling for a long time before abruptly ending his first-class career.

"I was committed and I'd said this to my wife [Virginia], I dreamed of winning a Shield this year and only spoke to [cricket performance general manager] Dave Moore after we'd lost to inform him," Cowan said.

"My intention was to win the Shield and I would've of course played through to see that out.

"There seems no point in me playing a game next week when we've got some seriously talented young batsmen that have been fighting for a spot. They deserve an opportunity and hopefully this game maybe one of them can score a hundred and it's the start of a great career.

"NSW cricket has a duty to provide a vast majority of Test players and if that's my attitude then we should be getting the next Steve Smith and finding who that is and giving them a game so that Australian cricket can maintain the rage."

Cowan fell victim to the NSW ethos earlier in the season when he was dropped for the opening Shield match of the season, despite finishing as last year's leading run scorer and earning himself the Steve Waugh Medal.

Daniel Hughes was picked in his place, a decision largely influenced by captain Steve Smith who was keen for his teammate to show his wares to Austalian selectors.

An emotional Cowan announced his retirement on Wednesday afternoon, but promised he would continue to play for Sydney University which is chasing back-to-back Sydney grade championships this season.

He reflected on a career which spanned 15 years and included a successful six-season stretch in Tasmania, book ended by his time at the Blues.

His time at Tasmania led him to a Test call-up, and Cowan made 1001 runs for Australia at an average of 31.28, scoring a century along the way.

"I look back with incredible fondness of all the memories, I feel proud, I felt like I eked every inch of output out of what I had and I never left anything in the tank," Cowan said.

"Could I have played more Test cricket? If the game pans out different ways and you get a call here and there, there are such small margins in the game right through.

"I've been thinking about it [retirement] for a while. There have been moments in the last couple of weeks where it became really evident that while I was still playing well and still feeling like I was contributing, those contributions weren't match winning.

"Often in teams gone by that killer instinct of turning a nice 60 into 150 and winning the game I really prided myself on. I Was getting out for 60 and 70 and not really minding if someone else had to do it.

"Those moments I thought this is not fair for the rest of the guys in the team."

A career in the media beckons for the eloquent Cowan who plans on taking a round the world trip before settling on his next move.

He did deliver one parting suggestion to Australian cricket officials, saying it was time this country adopted the full-time use of Dukes cricket balls.

"I know Kookaburra are great sponsors of club cricket in NSW particularly, but the quality of the Dukes ball, the evenness of the contest it provides, if I was an administrator working at Cricket Australia I'd be looking firmly at using Dukes cricket balls for Test cricket in Australia," Cowan said.

"We've just seen better games of cricket generally, we see the ball moving for longer, we see the spinners in the game a bit more. The way Test wickets have been in Australia the last couple of years, we need to see a more even contest."