The Queen came face to face with a sight today that would make any chocoholic groan - thousands of Maltesers destined for the scrap heap.
The sweet treats piled up in an enormous plastic bin were not up to the exacting standards of the world famous chocolate manufacturer Mars and will be melted down to be reused.
At the firm's UK headquarters in Slough, Berkshire, the Queen and Duke of Edinburgh were given a tour of the plant where the Mars bar was first produced and Maltesers invented.
The royal couple learned about the technology and skill used to turn raw cocoa beans into the finished product.
Talented chocolatiers from the facility founded by Forrest E Mars Snr in 1932 also showed off their skills by creating a carriage for the Queen.
Fiona Dawson, president of Mars Chocolate UK, took the Queen on the tour of the headquarters and said after the visit: "We were absolutely delighted to host Her Majesty The Queen and His Royal Highness The Duke of Edinburgh at Mars Chocolate UK.
"We have been manufacturing chocolate in Slough for over 80 years and it was a real privilege to have the opportunity to share our UK manufacturing heritage with our guests and introduce some of our fantastic associates.
"We have over 1,000 associates working on the site and everyone was thrilled to be part of the visit. It has been one of the most exciting days at Mars Chocolate UK since we first opened the factory in 1932."
Mars makes 2.5 million Mars bars at its Slough plant, which operates round the clock, and a host of other chocolate delights from Galaxy bars to Minstrels, Revels and Snickers.
The firm has become part of Slough's heritage after more than 80 years in the town and the royal couple met its longest serving staff member, Audrey Cook.
The 83-year-old joined the company in 1944 aged 14 and the sprightly pensioner now works in the staff shop.
She began her career in the "stripping room" where chocolate destined for Mars bars was cut into strips.
When the veteran worker told Philip about her first job she said he joked, "Oh, I thought it was something else", and when she said it was all done by hand the Duke quipped, "Most stripping is".
As the Queen was taken on the tour she resisted the temptation to try some of the chocolates being created before her eyes.
In the research and development kitchen, where new sweets are created before being manufactured on a large scale, staff demonstrated the processes used to make some of their best-known products.
Melted chocolate was tempered on a slab of marble - spread and constantly turned with a spatula - and the royal couple were told the process cooled it, ensured it snapped cleanly, added a gloss finish and ensured a smooth texture in the mouth.
Mars bars are the company's most famous product and caramel, freshly made in small copper pots, was cooled on a slab and later combined with nougat during a demonstration.
When it came for the top layer of chocolate to be added, Philip watched intently as a scaled-down machine coated the bars and he joked with Ryan Moulder, who was monitoring the chocolate as it passed by, asking: "You just stand and watch it?"
Before the Queen left she unveiled a plaque to mark her visit and was presented with the edible carriage - a replica of the Irish state coach - made from chocolate, sugar and 24-carat gold leaf.
Mars' president told the monarch: "It's the first time we've had gold leaf in one of our products. I hope it doesn't take off otherwise it might be expensive to make."
The Queen appeared pleased with her gift that also featured an edible painting of Windsor Castle complete with a gold frame and two M&Ms dressed as guardsmen, complete with bearskins, guarding the rear of the picture.
As she stepped forward for a closer look, the monarch said: "Yes, very clever, it's rather detailed isn't it?"
The Queen pointed out the chocolate carriage to Philip who said to the president: "You expect it to be eaten or kept?" before adding "Put it in your museum."
Chocolatiers Nicos Charalambous and Mike Zietek worked for a fortnight to create the carriage.
Mr Zietek said: "We've been making it for about two weeks, had a week of planning and a week of making and came in over Easter.
"We were thinking what could we make that had enough detail to show some skill and finesse, and something that would work well with chocolate."Suggest a correction