Frankie Dettori back centre stage today – but too late to gain part in Classic drama

Jockey takes first mounts after ban at Epsom, where O'Brien's Moth can land Oaks

Liber Nauticus won her trial at York but the contours of Epsom may not suit her so well (Getty images)

Frankie Dettori, having himself contributed to a miserable spiral of scandal among his professional community, finally returns to the fray at Epsom tomorrow. The timing of his comeback – on a Classic card, and on the eve of the greatest race run on British turf – gives him every chance of extending his own sense of relief to the sport as a whole. If nothing else, his instinct for theatricality would seem undiminished.

Dettori's six-month suspension, for a positive cocaine test at Longchamp last September, has since become a relatively trivial embarrassment for a sport convulsed by consecutive sensations. Last month Mahmood al-Zarooni, who trained for Dettori's former employers at Godolphin, was banned for eight years after administering anabolic steroids to his horses. And last week Eddie Ahern, one of Dettori's most talented rivals, was given a still longer suspension for his alleged role in a betting conspiracy.

It is not just the prodigal Dettori, then, who craves a fresh start. Even his return, admittedly, retains a residual quality of controversy. Due back at the beginning of last week, Dettori was denied his licence pending resolution of an unspecified "glitch" or "discrepancy" – in the words of his own team – in one of numerous tests supplied to the French regulators who had banned him. The British Horseracing Authority, bound by reciprocal arrangements, had no choice but to defer the return of his licence here.

With Epsom in mind, the BHA promised to expedite its own procedures as soon as France Galop had confirmed its own licensing criteria to have been satisfied. And it also stressed that Dettori would be permitted to replace jockeys nominated at the final declaration stage. That enables him to supplant Kieren Fallon on Beatrice Aurore in the first race, and Adam Kirby on Fattsota in the second.

Tonight the BHA confirmed that Dettori's licence had been duly restored after "confirmation from France Galop that he has successfully fulfilled all of their criteria to be fit to ride" – 16 days after he had satisfied the BHA's own licensing committee. One of the conditions is that Dettori, 42, "may be subject to enhanced testing controls" over the next five years.

The Italian is also set to partner First Cornerstone in the Prix du Jockey-Club at Chantilly on Sunday – historically treated as the French Derby. But the breakthrough came too late for Dettori to squeeze his way into the Epsom original, it having become increasingly fanciful that anybody might offer him a serious mount.

Epsom is one of the most difficult tracks in the country – as witnessed by the mediocre ride Dettori himself gave Blue Bunting when favourite for the Oaks two years ago. Had he made his comeback as scheduled, he would have had a dozen days to blow away the cobwebs. As it is, his mental and physical sharpness could hardly be equal to such a crucible on his first day back after six months.

Though he has ridden work at Ballydoyle this spring, a "cold" Dettori could hardly hope to replace Richard Hughes – a fairly rare booking for the yard, but a reigning champion jockey at the top of his game – on Mars. Aidan O'Brien's other four Derby runners are all ridden by Ballydoyle regulars.

O'Brien holds excellent prospects of winning his fifth Oaks. For a start, Say could build enormously on the foundations laid in maidens. She remains totally unexposed at a mile and a half, after coasting home from just three rivals in her only start at the trip, and the sheer depth of elite middle-distance prospects at Ballydoyle makes her very presence significant. O'Brien has a history of prompting a sudden bloom from fillies, in particular, after they have put in a fair bit of groundwork in maidens.

A case in point is his other runner. Both Say and Moth started their careers in the same maiden, at Navan last October, and finished more or less upsides in fifth and sixth. Like Say, Moth had contested three maidens before being fast-tracked to a Classic at Newmarket this month. As such, however – unlike Say, and nearly every other filly in the field – Moth arrives with Group One runs on the board.

For a filly bred to stay beyond a mile, Moth has run a couple of pretty extraordinary races this spring. She had been dazzling in a Curragh maiden over seven furlongs; then, in the 1,000 Guineas, she was asked to track the fancied Hot Snap, only to be caught out of her ground as it became clear that the favourite was running flat. Nonetheless Moth was making stylish progress when meeting traffic at a crucial stage, ultimately doing well even to snatch a place on the podium as she finished best of all.

Admittedly, the female milers may not be a vintage crop, but the one who finished just in front of her that day at least won the Irish 1,000 Guineas last Sunday. And, critically, Moth is entitled to improve again. First, her physique is developing all the time. Second, the big step up in trip should bring her latent stamina into play. Moth (4.00) did seem momentarily disconcerted by the Dip at Newmarket, and must deal with Tattenham Corner. But odds of 3-1 are sufficient to absorb that one reservation.

The favourite, Secret Gesture, is respected but her visually stunning trial at Lingfield is hard to measure, having been achieved in bad ground at the expense of a rival who gave herself no chance of lasting home by pulling. She plainly has loads of ability but is a short price for one who must now add substance to style.

Liber Nauticus will improve for the longer trip – which is just as well, so laboured was she in her rehearsal at York. With barely a fortnight to absorb that education, she could just take a little too much organising round Epsom. But Banoffee was ultimately impressive in getting herself out of trouble at Chester, while Michael Bell's pair can both improve on promising comebacks – Madame Defarge, in particular, looking value at 28-1.

Turf account

Chris McGrath's Nap

Blue Surf (2.10 Epsom) Has gone well fresh in the past and can resume last season's excellent progress for a yard in top form.

Next best

Decent Fella (5.40 Catterick) Very well treated nowadays and signs of revival over an inadequate trip last time.

One to watch

Tried over a longer trip, An Cat Dubh (Ian Williams) was left with plenty to do after meeting traffic at Chester last Saturday, closing well for fourth.