The Food Producers – Whirly & Gregorie Marshall of Blackthorn Salt, Ayr

Whirly & Gregorie Marshall

Salt: essential for human life; one of our senses of taste. The stuff which makes our food worth the eating. But there is more: much, much more. Did you know that there are over 14,000 things you can use salt for?

Whirly Marshall does, and her husband Gregorie can probably tell you what they all are. An expert on the subject, he is the fifth generation in the family business of Peacock Salt, the largest distributor of salt products in the UK. But until the two of them founded Blackthorn Salt, the actual production of salt wasn’t in the repertoire.

You’ll find Blackthorn HQ, appropriately enough, at 1 Saltpans Road, Ayr. I view and climb the strangest building you've ever seen, 25 metres long and 8 metres high, shaped like a giant wedge of cheese. It took a year to construct. This is a graduation tower, the first built anywhere in the world for over 200 years. It’s an eco friendly means of salt production, dramatically reducing the amount of energy required.

The Blackthorn Tower

The tower was built as an open frame, and the sides were then packed with blackthorn twigs, hence the brand name. Blackthorn is incredibly hard wearing and with all the jaggy bits they form a huge surface area. Seawater is repeatedly filtered down the structure, reducing 26,000 litres of water to 2000. The evaporation occurs naturally using sun and wind. The remaining liquid is then heated to release the salt crystals.

Of course it’s not that simple. It took 15 years to get up and running as endless experiments were made, not least on the precise siting and angle of the tower. Gregorie’s training as an architect came in handy.

The timing is very weather dependent. Whirly (that is the name on her passport, in case you were wondering) tells me that on average it takes a week to do a batch, but it has varied between three weeks and twenty four hours. It’s something which needs to be checked a few times each and every day. Gregorie has the able assistance of Malky, who has been involved in the business since he left school. Apprentice salter – how many folk can list that as their occupation?

We visit the Pan House where the final product appears. Centuries old technology gives way to state of the art sensors. Then we go back in time again to the office – in a converted railway carriage. Blackthorn is being marketed as a premium product. Great – and I applaud their use of plastic free boxes. But what exactly does premium product mean? Isn’t it the case, I suggest, that salt is just, er, sodium chloride? What makes your sodium chloride different from anyone else’s?

Whirly gives a sigh and smiles. She’s heard that one before. The demonstration is about to begin. Four types of salt are put on a plate and a bowl of halved cherry tomatoes is produced. We sample these with a little of each salt in turn.

The first one, a well known market leader, is 99.9% sodium chloride. It tastes harsh and rather unpleasant. The second, pink Himalayan, looks pretty, but at around 98% doesn’t have much going for it taste wise either. Another crystal version is markedly better. Bizarrely it allows a bit of sweetness to come off the tomato. But, you’ve guessed it, the best has been kept till last.

I really never ever thought I’d go wow! at a taste of tomato and salt. The completeness and range of mouth flavour is quite remarkable. Because Blackthorn isn’t refined to within an inch of its life, it contains calcium, potassium and magnesium. Constant exposure to the twigs gives the final liquid a brownish hue, This is caused by tannins, which in turn add a savoury umami flavour. In short Blackthorn is activating more of your taste buds. The flavour of that last tomato lingered so much longer in the mouth.

The Blackthorn Team and The Hairy Bikers

The penny drops. Blackthorn isn’t just sodium chloride. That’s why it has been used by William Curley, Britain’s top chocolatier (originally from Methil, I discover).  Whirly proudly tells me that their customers are widely varied. They include manufacturers of soap, butter and cheese; those interested in spells and witchcraft; and a mermaid. Oh, and I nearly forgot to mention top chefs such as Michel Roux and James Martin. Spending time in the area, I was delighted to see Blackthorn's distinctive packets in a wide range of retail premises.

You may have seen them featured recently on the Hairy Bikers latest GB jaunt. The boys actually visited as long ago as 2021, but the programme was transmitted only this year.

I could have spent the rest of the day munching bread, tomatoes and salt, but we are then given tiny slivers of water melon and invited to pop a grain of Blackthorn on each. Eh?! Well I knew that salt was an intensifier of flavour, but this was off the scale. In a short period they have picked up a slew of awards, including a Platinum and a Gold Award at the Scottish Food & Drink Awards, plus a 2 star rating from the Guild of Fine Food Great Taste awards.

In real terms, because of COVID, the business has had only a couple of years of trading. Whirly says they are happy with progress so far. Where next? A ringing endorsement from Si and Dave didn’t do any harm, but there is a whole world of prospective consumers out there. Two more of them are to be found at the Tom’s Food! HQ.


Click here to see the Blackthorn website, and here to see clips of the Hairy Bikers' visit. You can also catch the full episode of that programme here. (On BBC iPlayer - BBC account required.)


  1. Janet Hood on 21st June 2023 at 8:06 am

    I love this salt – discovered it a couple of years ago and have never looked back.

    • Tom Johnston on 21st June 2023 at 7:04 pm

      Couldn’t agree more.

  2. Carole hope on 21st June 2023 at 8:27 pm

    I never thought salt could be subtle until we were given some of this. I would have described us as very anti-salt. We never add salt to food on the plate and have complained about the oversalination of dishes in MIchelin starred restaurants – although only on this side of the channel. We are very sparing in its use in cooking. This salt is a delight – it enhances a dish instead of ambushing it. Tom, I know you won’t agree with our general take on salt, but at least in this we are agreed, which is sweet – or even gently salty ?

    • Tom Johnston on 22nd June 2023 at 9:47 am

      Not sure why you think I would disagree with you, Carole. A matter of personal taste. The eye opener for me was a cookery class at Martin Wishart’s cookery school (where The Little Chartroom now stands). I think professional chefs use more salt than we do at home, but they pointed out that it’s a flavour enhancer as well. Try the Blackthorn test. Put a single grain of their salt on a cube of water melon. Wow! I don’t add a great deal of salt after cooking, tatties excepted.

  3. Paul on 22nd June 2023 at 8:46 am

    Fascinating stuff. I was brought up with a tub of Cerebos but since then I have moved on to various salts of differing qualities. I do enjoy using freshly ground salt as I do with black pepper.

  4. Michael Greenlaw on 22nd June 2023 at 3:46 pm

    An intriguing venture all round.
    The salt sounds wonderful, Tom and the Graduation Tower looks impressive and I like the sound of the railway carriage office.
    I remember the old Cerebos salt works beside the Water of Leith and the old Balerno branch railway line at Colinton, hard by the former Scott’s Porage Oats factory.

    • Tom Johnston on 23rd June 2023 at 8:45 am

      Before my time. The Blackthorn experience was just stunning, as is the flavour.

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