But the race was marred by a tragic starting stall accident to another outsider, Gray Pearl.
A very subdued crowd at rain-sodden Newmarket greeted jockey Ryan Moore in the unsaddling enclosure as he echoed the sentiments of every racegoer when he said: "It's very sad."
The start was delayed by more than half an hour when Gray Pearl became wedged under the stalls in a freak incident that came one month after two horses were killed in the Aintree Grand National.
The other runners were withdrawn from the stalls which had to be removed in a bid to extricate the stricken filly. Racegoers feared the worst when screens were put up across the centre of the course and Gray Pearl had to be put down after suffering what vets called "an apparent spinal injury".
"To minimise distress to the filly. a decision was made to have her put down on welfare grounds," said veterinary officer Chris Hammond.
Moore said: "It was very sad with Gray Pearl and the lads (the starting stall handlers) were doing all they could down there for her."
O'Brien won the 2000 Guineas on Saturday when the hotly fancied Camelot landed the first classic of the season in the hands of his lanky teenage son Joseph.
On Sunday, Joseph's mount, the 13-8 favourite Maybe, could only manage third place behind her much less fancied stable companion.
Homecoming Queen's victory was certainly no fluke. The filly, recalling the style of Frankel's imperious victory in last year's 2000 Guineas, spreadeagled the field to land the fillies' prize in effortless style from 33-1 chance Starscope.
O'Brien, who last achieved the Guineas double in 2005, was not as surprised as most punters by the extraordinarily easy victory of Homecoming Queen.
"She certainly is a very good filly. She has a big heart," he said of the compact little filly who did not win as a two-year-old until her eighth attempt.
Moore could not believe how easily he had won. "I thought I was going a stride too quick but she just kept going." But he did not get carried away, saying: "I don't think we can compare her to Frankel."
Homecoming Queen was running the 14th race of her short career against some much less exposed fillies and Moore was full of admiration, saying: "There's not much of her but she is very tough."