Queen Elizabeth II wears lime green Stewart Parvin to celebrate her grandson Prince Harry's wedding to Meghan Markle

As the sun shone downin Windsor this morning, many guests chose towear bright colours.

But brightest of all was Her Majesty Queen Elizabeth II, whochose a lime green silk tweed coat with frogging detail layered over a subtly flared printed silk dress in complementary shades of lime, lemon, purple and grey, both by Stewart Parvin.

To top it all off, HM chose a hat made in the same lime silk tweed by Angela Kelly, her personal assistant and senior dresser, who is also a designer and milliner.

An arrangement of purple flowers tied the colours together, while handmade lace crystals and pearls by Lucy Price added a little sparkle in the sunshine.

As is her signature, the Queen wore a brooch pinned to her left shoulder - the Richmond Diamond brooch with pearl drop.

The brooch was gifted by the town of Richmond to Queen Mary on the occasion of her wedding to the future King George V. Queen Elizabeth II wore the brooch to her 90th birthday celebrations in 2016.

In the past, the colour blue has proven to be afavourite with the Queen, who has worn different shadesto particularly important weddings, including those of two of her sons, Princes Charles and Andrew, her daughter Princess Anne, and her sister, Princess Margaret.

But it seems that the Queen has tired of blue, as she"sfavouredsomething a little more uplifting in recent years.

This lime green is much more in keeping with the sunshine yellow that she chose for the Duke and Duchess of Cambridge"s wedding in 2011: both are citrus shades, and both are optimistically bright.

But we can still see signatures of the Queen"s classic style here.Over the years, HM has established something of a uniform for the many weddings she attends.

A brightly coloured (so that she can be easily spotted by the public) coatis layered over either a matching dress, or a printed dress in a complementary shade.The hat usually matches the coat.

Whatever colour the Queen iswearing, her bag, gloves and shoes will only ever be black or white, usually - but not always - all matching each other.

Launer London, the maker of the Queen"s favourite handbags, saw a 60 per cent increase in sales of their most traditional styles after HM wore a cream bag by the brand to the Duke and Duchess of Cambridge"s wedding in 2011.

Green may not have been a favourite with the bookies, but it just goes to show that even after attending hundreds of weddings, HM can still surprise us all.