will soon celebrate its 900th episode - but there are some strict rules in place to ensure everything runs smoothly on one of the nation's best-loved shows. A volunteer who worked on set for an entire day has revealed that they were under instructions never to touch any of the items being valued - even if the owner of the potentially pricey collectables asked them to do so.

The worker, who took to offering to spill secrets about the show, elaborated: "There were several instances where owners dropped their objects. One woman dropped a vase that was valued at a couple grand... she flipped! We were told explicitly by the producers to not touch ANY of the guests items, even if the owners were asking for assistance." She also let slip another major no-no - appraisers offering to buy the items.

No matter how much interest they might have, they are instructed beforehand not to proposition the guests.

"The appraisers do not offer to buy items on the spot, because it would be totally unprofessional," the worker continued, explaining that they are only free to "express interest".

If they want to negotiate a price for an item, they can pick up appraisers' business cards, "which are all set out on a huge table as the guests leave the event" - but not everyone chooses to leave their details.

Besides revealing these two major rules, the Reddit user also offered curious fans an insight into the research process before the cameras start rolling.

"How much research do the appraisers (or assistants) do for an object? What's the time line between when they first see something, and when they make their final analysis?" quizzed one.

The worker, who goes by the name wellmeomy, replied: "All of the research is done on the day of the event. The appraisers take usually about an hour, but some time more, to collect their information.

"There is a small area backstage with computers and a book collection to use for reference, although it seems most of the appraisers can assess the more common items instantly without much research."

It's little surprise that there's huge interest in the BBC show, as it's racked up a whopping 866 episodes across 47 series since its debut 46 years ago, and is as popular as ever.