While Skrei is a reasonably new ingredient to these British chefs, the export has been a crucial part of Norway’s food culture and economy for thousands of years. ‘Our country has been built on this fish,’ explained Amund Bråthen, a cod specialist from the Norwegian Seafood Council (NSC). ‘There’s a Viking story dating back to 875 AD that talks about Vikings drying and shipping Skrei, and there was so much income from the fish around year the 1000 AD there were cathedrals built with the money. It was a protein source the Vikings could keep when they were away and export to England.’

Amund is also adamant that Skrei is crucial to the country’s future. ‘We have oil, which will run out, and then we have fish, which we've understood for years. It's important for us to fish it sustainably because this is what we will live off for years to come. We need to protect it.’

Norway’s careful policing of its waters and sustainable fishing quotas was self evident as soon as we were thrillingly passed by feeding groups of orcas. Within a few minutes of stopping and dropping our lines, a few nautical miles west of the fjord of Malangen, Ollie Dabbous was reeling in his first fish – not bad going for a first time fisherman. ‘What I love about this fish is the texture of the flesh,’ he told me. ‘It’s got this amazing firmness to it and it never feels pappy or fatty, which you can sometimes get with other big fish.’

Robin Gill, who grew up fishing off the coast of Dublin, was particularly impressed by what he saw on the boat. ‘We should all be taking a massive leaf out of the Norwegians’ books,’ he explained. ‘They control all their own waters and they take real pride in it. The fishing here is the best in the world and the most profitable, and you can see how healthy it is; the moment you put a rod down you catch fish. If you’re in charge of your own fishing policy you’ll look after it all.’

It’s not just the sustainable policy which impresses us during the visit, but the way the Norwegians quality control the labelling of Skrei. During the season, hundreds of millions of the fish flood into Norwegian waters, but only about five to ten percent of what is caught is allowed to be labelled with the special ‘Skrei’ mark on its dorsal fin.

After four hours of fishing – during which we collectively pulled in a lively mix of Skrei, cod and coley – we moored up beside the small Skrei processing plant in Kvaløya to understand for ourselves how stringent the Skrei controls are. We were met by Kjell-Arne Pedersen – a member of the Skreipatruljen, or ‘Skrei patrol’. His job is to police the sixty-nine packaging plants across the Norwegian coast to make sure they are adhering to the strict Skrei criteria. If they’re found to be packing Skrei that isn’t up to standard, the NSC will sanction them, closing them down for a minimum of four days until the mistakes are rectified.

Inside, Kjell-Arne showed us crates and crates of pristine-looking cod which did not make the grade, and the chefs are shocked as they all look like beautiful specimens that would fetch a high price at any fish market. We were assured that this fish will still be sold as cod, fresh and dried, but to be graded as Skrei it must be in perfect condition – without any marks on the skin; bled out at sea and rinsed with sea water slush to ensure the whitest flesh, before being kept at 0–2°C to ensure a state of pre-rigor that guarantees absolute freshness for twelve days.

We were also pleasantly surprised to see the local children of the village getting involved in the industry, earning pocket money (up to £130 per day) by cutting out the cheeks and tongues of the cod at a very impressive speed. ‘It’s fantastic to see kids learning these hands-on skills from such a young age,’ said Simon. ‘The whole community seems to be involved, and I think we could learn a lot from this approach in the UK.’

‘We try and use every bit of the cod,’ explained Amund. ‘We use the roe and liver, which is very important because it contains high levels of vitamin D; something we all need at the moment because there is no sun.’ Upstairs above the factory, we sampled a very traditional lunch, cooked for us by two local sisters – Unni Lorentzen and Trobjørg Lindquist (as seen in our video) – which showcased this nose-to-tail approach to cod. As well as butter-fried cod’s tongues, they made us the time-honoured dish of Skreimølje, a protein-packed nose-to-tail dish using the roe, fillet and creamy liver of the cod, cooked in its own oil, that traditionally nourished the workers who would row up from the south to make their living fishing during Skrei season.

For Robin Gill, this lunch proved an inspiration, and got him thinking about future ways of using the fish. ‘I’ve had cod tongues before and never been mad on them,’ he told me. ‘These were lovely though. We’ve used the roe and liver before in the restaurant and this just re-emphasised the importance of using every part of the fish.’ The clarity of the water is also something that got Daniel Galmiche excited. ‘I want to preserve that amazing freshness we experienced,’ he said. ‘I’ll vacuum pack the fish and poach it with olive oil, then serve it with a white bean purée and ragu.’