There is no change in recipe, just they have been tested to prove they are gluten free by UK standards. The update is showing on supermarket websites, declaring that they are now gluten free certified and "cross grain trademarked" which means new labels will either have the cross grain logo or say gluten free on them. This doesn't mean existing stock isn't safe if just means they were produced before the testing took place. They may also decide to not print it and instead just update their website with the gluten free status, though they would be silly not to print on the label it is gluten free certified.
Coeliac UK and FDA used to say barley malt extract in vinegars were safe until a couple years ago when they backtracked and basically said "we don't know it actually falls below 20ppm so barley malt should be avoided in anything, including vinegars, unless labelled gluten free" and told coeliacs to avoid.
Mizkan have now gone through lab testing so they can legally say Sarsons malt vinegar and Branston Pickle is below 20ppm - I am sure this will make a lot of coeliacs happy. Lab testing costs companies a fair bit which is why so many don't bother doing it unfortunately.
Branston and Sarsons websites have now been updated to reflect that Branston Pickle is now gluten free and they have updated their FAQ with all the necessary information. The following products are now certified gluten free
Branston Original Pickle 360g
Branston Original Pickle 520g
Branston Original Pickle 720g
Branston Small Chunk Pickle 360g
Branston Small Chunk Pickle 520g
Branston Small Chunk Pickle 720g
Branston Original Piccalilli 360g
Branston Small Chunk Piccalilli 360g
Branston Original Piccallilli 280g
Sarson’s Malt Vinegar 250ml
Sarson’s Malt Vinegar 284ml
Sarson’s Malt Vinegar 400ml
Sarson’s Malt Vinegar 568ml
Sarson’s Distilled Malt Vinegar 250ml
Sarson’s Distilled Malt Vinegar 284ml
Sarson’s Distilled Malt Vinegar 400ml
Sarson’s Distilled Malt Vinegar 568ml
They also state they are working on making the following gluten free but aren't yet.
Branston Rich & Fruity sauce 245g
Sarson’s Dip & Drizzle – Garlic
Sarson’s Dip & Drizzle – Garlic
Sarson’s Distilled Pickling Vinegar
Sarson’s Malt Pickling Vinegar
Sarson’s Gravy Browning
Sarson’s Worcester Sauce
Sarson’s Red Cabbage
Sarson’s Sweet Onions
Sarson’s Silver Skin Medium & Tangy
Sarson’s Hot & Spicy Onions
Sarson’s Mixed Pickle
They state in the FAQ's (brand and site are cited on each individual website with the rest of the text being identical) "We’ve been working together with Coeliac UK to add a gluten-free claim and the Crossed Grain trademark to our Branton/Sarsons products. Together, we’ve made the necessary changes at our Bury St Edmunds/Meddleton site to ensure we can claim our products are gluten-free so that the coeliac community can enjoy the hit of home that Branston provides!"
They have some other useful info on their websites too - each websites FAQ states the same just with Sarson or Branston products and production sites changed.
Here is the updated allergy info on Asda and Sainsburys websites for Sarsons and Branstons too.