Four key contenders for the Coral Scottish Grand National

First run in 1858, the Coral Scottish Grand National is firmly established as the highlight of the jump calendar North of the border, and forms the centrepiece of a cracking two-day card at Ayr this weekend.

Despite the regulation fences and the maximum field of 30, the nigh-on four-miler lacks nothing of the drama of its Aintree equivalent and has often proved a precursor to glory in the World's most famous horserace.

Trend-wise the race defies categorisation, with novices and seasoned chasers young and old represented on the Roll of Honour, and with little rain forecast stamina may not be at the premium it can often be.

Welsh handler Christian Williams had the first two home last year and has compiled an enviable record in these stamina tests over the last few seasons – he saddles the ante-post favourite Kitty's Light.

Below, views on his chances and a few other interesting contenders among the final field of 23. Click here for all the runners and riders, plus the latest betting.

Trainer: Christian Williams. Best odds: a general 9-2

Denied only by thrown-in stablemate Win My Wings here last season, Williams's seven-year-old, already a veteran of many a marathon, can race off a 3lb lower mark this time and looks the most logical answer to this conundrum.

Never out of the first three at distances beyond 3m 2f and a confirmed Spring horse, the market leader can lack fluency and a gear or two early in his races, but few come home more strongly and he looks impossible to keep out of the frame in what looks a wide-open contest where few are guaranteed to get home.

Trainer: Nicky Henderson. Best odds: a general 16-1

At first glance the topweight appears to have a job on here after a truncated and disappointing campaign, with no form beyond three miles and giving upwards of 7lb to all his rivals.

However, after Shishkin's Aintree heroics few will dare to question trainer Nicky Henderson's judgement regarding his eight-year-old's stamina, and Dusart's defeat of Sounds Russian at this venue last season has acquired a golden glow given the latter's subsequent progress.

It could be that he has a pronounced class edge in this company provided Henderson has got him straight, and he must go close if his stamina holds out.

Trainer: Gavin Cromwell. Best odds: 14-1 with William Hill and bet365

Bids to become the first six-year-old to land this prize since Earth Summit in 1994, and proved a revelation upped to 3m 4f at Downpatrick last time out, coasting home in the Ulster National and looking as if a further half-mile would be well within her compass.

This undoubtedly represents a steep rise in class, but with fourteen chases under her belt already Gavin Cromwell's youngster lacks nothing in experience and may prove the pick of the Irish challenge.

Trainer: Paul Nicholls. Best odds: a general 20-1

No current trainer has a better record in this race than Paul Nicholls, and with Threeunderthrufive's stamina in doubt, Flash Collonges may emerge as his principal contender here.

Another untested over further than three miles, the eight-year-old is yet to match his hurdling achievements over the larger obstacles but has looked very much a work in progress and broke his chasing duck in a decent Novices' Handicap at Newbury last time out.

Likely to be on or near the pace throughout, the Ditcheat inmate could easily come on further and can give each-way backers a decent run for their money.