A week may be a long time in politics, but seven days proved plenty of time in the racing world as well, as the Aidan O'Brien-trained Serpentine progressed from winning a Curragh maiden to claiming the Investec Derby at Epsom.

The 25-1 shot made all under Emmet McNamara to give his handler an eighth win in the most prestigious of the European Classics, with Khalifa Sat (50-1) - who raced in second throughout - filling the runner-up berth. 

Serpentine's stablemate Amhran Na Bhfiann (66-1) denied 2000 Guineas winner Kameko (5-2F) for the final minor placing. 

English King stayed on for fifth and Mogul - the choice of Ryan Moore of the six-strong Ballydoyle battalion - was sixth.   

The finishing order was just as it was rounding Tattenham Corner, with McNamara's mount well clear from Khalifa Sat and Tom Marquand in second, and Amhran Na Bhfiann and William Buick occupying third.

The leading fancies threw down their challenges inside the final two furlongs, but they proved futile, as Serpentine had five and a half lengths in hand at the line. 

McNamara said of his first Classic win: "I think I got a little bit of a freebie. I had huge amount of confidence in the horse having spoken to Aidan during the week.

"He said he was a horse that is going to stay a mile and six well. He said jump, go your own tempo and just from halfway, from the six to the five, give him a breather. He said he'll keep going and he was right.

"All I could here was the horse breathing. He was in a good rhythm. He was relaxed and I couldn't hear a thing around me.

"I didn't want to be looking. I wasn't sure, but I knew I was a few clear all right.

"It's a bit surreal. I can't believe it."

The popular view will be that the winner was gifted an easy lead in a slowly-run race and that his rivals were given too much to do.

However, the time for the race was just 0.37 second slower than that clocked by Love in her record-breaking Oaks victory, while the early fractions weren't dissimilar to those set by Tiempo Vuela and Passion. 

McNamara was particularly enterprising on Serpentine in the middle part of the race and the advantage accrued there was dwindling as they approached the line, but the buffer wasn't eroded in a manner that would suggest he was a fortuitous winner.