Grimsby Town 0 Cheltenham Town 1: Cheltenham promoted after Ward's 'over-achievers' make Grimsby pay

Hailing from a place where horse-racing, rugby and cricket take sporting supremacy, Cheltenham Town know their position in the scheme of things but for one afternoon at least, here in Cardiff's Millennium Stadium, the football team claimed pole position in local hearts by winning promotion to League One.

It was the biggest crowd the Robins had ever played to. The four-legged beasts in the Cheltenham festival have seen far more but John Ward's side were unfazed by the size of the occasion and after going in front through Steve Guinan's second-half strike, they held on to their deserved lead. They could even afford to miss a penalty 20 minutes from time.

Yet their opponents will feel a deep grievance this morning for not only did they see an automatic promotion position slip away from them on the last day of the season, they also beat Cheltenham home and away in the regular league campaign. Adding insult to injury was a penalty claim that was not awarded before the half-time interval and after that, Grimsby barely troubled Shane Higgs in Cheltenham's goal.

But form horses mean nothing in the play-offs and Ward's men recognized that fact by starting the brighter, despite Grimsby being strengthened by the presence of their top scorer Gary Jones. Sent off in the semi-final against Lincoln City, his red card was rescinded but he was a peripheral figure here for most of the afternoon. When he did have a strike at goal, his header from close range was pushed away by Higgs nine minutes from time.

By then the Mariners were chasing the game thanks to Guinan's unexpected strike after 63 minutes. Taking the long way round the penalty area, the forward's effort was a cross rather than a shot that eluded everyone on its way past Steve Mildenhall in goal. Helped by some defensive uncertainty, Cheltenham need not have waited so long to take the lead. On two occasions Rob Jones was found out in the air but he was bailed out each time by his goalkeeper.

Grimsby's riposte came with a penalty appeal when Andy Parkinson was tripped inside the penalty area with nothing awarded. Having not seen a replay, their manager Russell Slade only said "we felt strongly about it", before adding graciously: "It didn't really happen for us. We're very disappointed. Cheltenham on the day were the slightly better side."

One penalty that was given came when McCann was tripped by Curtis Woodhouse and Mildenhall read his spot-kick well to save it. It did not matter, much, to the relief of Ward who said: "I'm thrilled. It's the best thing I've ever done. We've taken two years to put this together and that's what has pleased me most. We have over-achieved in a short space of time. Now I'm looking forward to seeing this group of players in the next league up."

Goal: Guinan (63) 0-1.

Grimsby Town (4-4-2): Mildenhall; Croft (Futcher, 75), Whittle, R Jones, Newey; Mendes (Goodfellow, 84), Woodhouse, Bolland, Parkinson; Reddy (Cohen, 33), G Jones. Substitutes not used: Kamudimba, Toner.

Cheltenham Town (4-4-2): Higgs; Gill, Duff, Caines, Armstrong (Bell, 33); Vincent (Spencer, 78), Finnigan, McCann, Wilson; Guinan, Gillespie (Odejayi, 57). Substitutes not used: Brown (gk), Bird.

Referee: P Taylor (Hertfordshire).

Man of the Match: McCann.

Attendance: 29,196.

The FA will investigate claims of suspicious betting patterns surrounding a League Two match played last season. Correspondence was received on Friday from a professional gambler who spotted "significant sums" being staked in the Far East on one side winning the match by a margin of more than one goal. That result was achieved.