By Cornelius Lysaght BBC racing correspondent

Former jockey Stack, now a trainer, is a legend among racing fans

For many, Tommy Stack will be forever associated with that emotional April afternoon in 1977 when he guided Red Rum to an historic third Grand National success at Aintree.

It's been ranked amongst the outstanding moments in British sporting history, as 'Rummy' added to his wins of 1973 and 1974 - plus two second places - in the world's greatest steeplechase.

But, after being forced into retirement by injury within a year, aged 32, always-popular, dual champion jump jockey Stack determined to make a new mark training racehorses back home in Ireland.

Setting up shop in 1986 in the County Tipperary village of Golden, he soon started to shine.

The 1000 Guineas at Newmarket came his way in 1994, via Las Meninas, while a little known Jamie Spencer steered Tarascon to success in the Irish version four years later.

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Unsung Heroine, a bay-coloured filly who started her career rather belatedly, is now the apple of their eye after recording two successes from two starts.

It was after her latest win, a good one at Cork, that the filly became a serious candidate for Doncaster's Ladbrokes St Leger, the final Classic race of the British Flat racing season.

She will be the stable's first contender in the race, and it turns out that an anticipated 'decent run' would be just reward for the patience of the whole team.

Stack junior told me: "Although Unsung Heroine's won both of her races well, she seems to like to do self-harm as well, and stood on herself in the spring while having a pick of grass.

"She sort of bucked and kicked and did the damage and spent two weeks in the veterinary clinic being put back together again. Plans to go for an Oaks trial and the Irish Oaks had to be scrapped.

The 232nd St Leger has a particularly wide-open look to it, with Aidan O'Brien having all sorts of chances to enhance his already prolific season Cornelius Lysaght

"Her two wins have been good performances for an inexperienced filly - she stays well - but she probably needs to step up again. She's had a nice rest since Cork to try and do that."

The 232nd St Leger has a particularly wide-open look to it, with trainer Aidan O'Brien having all sorts of chances to enhance his already prolific season.

Additionally, the Epsom Oaks winner Look Here brings Classic-winning form with her; Sir Michael Stoute has three runners as he seeks to nail his bogey in the biggest domestic race he's never won; while Top Lock is likely to stay the extended distance.

But victory for Tommy Stack would be perhaps the most appropriate, the neatest.

Because it was at Doncaster, in November 1970, that Stack the jockey rode Red Rum on his first step towards superstardom when the horse won his first steeplechase.

He was, of course, a 'sung hero'; now an unsung one is clearing her throat.