It was a bold salmon-pink design that sparked fierce debate among the Tartan Army when it was first revealed.

Some fans didn’t initially take to the colour while others hailed its retro look.

But the away kit for Scotland’s team at this year’s World Cup has become a must-have fashion item. Demand has rocketed and shops sell out within days of getting new stock.

Now, its lead designer has spoken of his pride at seeing the Tartan Army decked out in its distinctive shade.

Sergio Mareco, a senior designer at Adidas, said the shirt involved ‘a lot of research into national identity, history and culture’ as the design team looked to create ‘something that would work on matchday but also as a lifestyle piece’.

He added: ‘The away jersey nods to the history of some of Scotland’s classic kits and reintroduces scarlet red tones.

‘With this specific shade that stands out so much, being punctuated by thin, purple stripes, we knew that we had an iconic design that fans would love.’

Brazilian Mr Mareco began his design career in his home country before joining the Adidas football apparel division at its global HQ in Herzogenaurach, Germany.

Asked if he felt proud at the kit’s reception, he said: ‘Absolutely. That’s probably one of the most satisfying parts of the job. 

'We create these shirts with the supporters in mind, so seeing thousands of people wearing them together, representing their country and creating that sea of colour is incredibly special.

‘It reminds you that the shirts become part of people’s memories and experiences.’

Tens of thousands of fans, including celebrities such as TV presenter Hayley McQueen and Hollywood star Karen Gillan, donned the pink shirt for Scotland’s games.

And Mr Mareco said: ‘Seeing such a positive reaction from supporters is the best feedback you can receive.

‘When a shirt sells out, it tells you that people have formed a genuine connection with the design.’

The Tartan Army made a lasting impression during their time in the States, with American media recounting their exploits, including placing traffic cones on statues heads, on a daily basis.

Discussing his own take on Scotland's fans, Mr Mareco said: 'Scottish football fans are amongst the most ardently passionate around the world, and we’ve seen that again this summer in the States. 

'We saw in Boston how the city took to them and they put such a big Scottish stamp on a city already steeped in culture and history.'

He added: 'Scotland fans have a way of bringing people together, and that sense of community is very special.'

He also said he'd love the chance to design more Scotland kits in future.

He said: 'Scotland has such a rich visual identity and such passionate supporters that allows for so much creativity. 

'Every new cycle presents an opportunity to tell another chapter of the country's football story, and that's an exciting creative challenge.'

He added: 'Scotland offers so much creative inspiration — from its landscapes and architecture to its textile heritage and sporting traditions. 

'The challenge is always finding new ways to celebrate those influences while creating something that feels unexpected, modern and instantly recognisable as Scotland.'