Thinking of ‘Scotland’ and ‘industry’, and most people picture grimy cities: mines, mills, shipyards and railways. They probably don’t think of a beautiful boat trip on the west coast of Scotland.

But that was where my journey started for the final episode of Series Two of Scotland from the Sky.

Just south of Oban there’s a whole network of islands. On the last day of August last year, in beautiful sunshine, I headed off from Cuan sound to one of the smallest – Belnahua.

The abandoned island of Belnahua was once a bustling centre for slate production

It’s a genuinely haunting place. Rusting machinery and ruined buildings point to an intensive industrial past, to work that changed the entire island forever.

Massive industrial quarries – over 60 feet deep – were dug here for one bustling business: the production of slate. At the industry’s peak – at the end of the 19th century – Belnahua was home to over 200 people. But by 1920 the sea had broken into the deep quarries and flooded them, making them useless. The slate industry was ending.

From Belnahua, we wanted to go much further back in time, in search of something that’s not industrial, but which would gradually help make industry possible. A road. But not just any road. We were looking for the first ‘main road’ ever built in Scotland – the work of the Romans nearly 2,000 years ago.

Using a vintage Tiger Moth, we set off towards the Scottish Borders, looking for what is known as ‘Dere Street’. It once ran for over 200 miles from the city of York all the way into Perthshire.

The cooling towers at the gigantic Ravenscraig site

Seeing it from above was remarkable – not just to appreciate the skill and ambition of the Roman builders, but also to view how the past and present can still live side by side, as the ancient road merges with the modern one, to become the A68.

Next, we moved far to the north west to Loch Maree in Wester Ross, once  a massive industrial centre. Alongside a fast flowing burn – known in Gaelic as Abhainn na Furneis,  ‘the river of the furnace’ – we found the remains of what would become one of Scotland’s biggest industries: iron.

Four hundred years ago, this was the site of Scotland’s first ever blast furnace with 300 acres of trees felled from the surrounding forests to make ferocious heat to create iron.

From these beginnings at Loch Maree, we wanted to track how heavy industry came to take over and transform Scotland’s Central Belt. Our next stop was a business that began near Falkirk in 1759, and would grow to become one of the biggest and most important iron works in the world: Carron

The Carron iron works led the way for the vast industrial sites that would spring up all over the Central Belt: coal mines, quarries, factories and shipyards.

To truly grasp the huge impact of heavy industry on this part of Scotland, we needed a helicopter. Taking off from Cumbernauld we continued on to what, for me, was Scotland’s most iconic industrial plant: Ravenscraig. In its heyday it was the largest steel-maker in Western Europe – producing some two million tonnes per year. Today it is Europe’s largest waste ground – 1,000 acres, so large you could fit 700 football pitches inside it.

After Ravenscraig, headlines talked of the end of heavy industry in Scotland but at the other end of the country, construction of the colossal Sullom Voe oil terminal was soon to begin. In just a few years, an empty peninsula was completely transformed. Ten million cubic metres of peat were moved to lay 300,000 cubic metres of concrete, 25 miles of road and 150 miles of pipeline.

I was born on Shetland in 1978, a year after my father arrived on the islands to help build Sullum Voe. This was the beginning of the oil boom in Scotland.

But in my lifetime, I’ve seen the business pass its peak. One day, this industry too will disappear - but its traces and memories will not.

When we look down on our past from above, we can still see our industries – and the stories of the people who have worked in them – written all over our landscapes.

Scotland’s lost industries are still embedded in the landscape