LONDON -- We're not sure if it's the Tesco vouchers, winning on the horses or some combination of the two that's made the Queen so deliriously excited, but one thing's for sure: she's having a really, really good day.

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The Royal Windsor Horse Show took place on Thursday in the grounds of Windsor Castle. There were plenty of horses in attendance, such as these glossy white beasts.

The whole thing is about as British as it gets.Credit: Ben Cawthra/Sipa USA

Also in attendance was Queen Elizabeth II, seen here studying a different horse. 

This year's event ties in with Her Majesty's 90th birthday.Credit: Andrew Matthews/PA Wire

The excitement started when the Queen's horse, Barber's Shop, triumphed in the Tattersalls & RoR Thoroughbred Ridden Show -- and earned Her Majesty a special prize.

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Here is what we can only assume is the source of all her happiness.

Oh hell yes.Credit: Andrew Matthews/PA Wire

We don't know what the value of that voucher is -- or whether or not the the Queen is a regular Tesco shopper -- but frankly these are minor details. Sometimes the winning is all that matters.

Best.

Credit: Andrew Matthews/PA Wire

Day.

Credit: Andrew Matthews/PA Wire

Ever.

Credit: Andrew Matthews/PA Wire

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