Beyond Port Maxwell, the Union Canal rejoins its original 19th-century line. A couple of canoes are paddling around near the Seagull Trust’s efficient modern boathouse as we slip quietly along the leafy waterway and plunge into the depths of Falkirk Tunnel.

It’s cold in here, with water streaming down the bare rock walls. The steady chug of the engine echoes around us as we admire the striking ochre, cream and rich grey tones of the rock strata glistening in the lamp light. After ten minutes underground, we emerge into a wooded cutting beneath the much-photographed Laughin’ and Greetin’ bridge.

With a crew of friends, I’d settled into the Black Prince narrowboat Fiona the previous afternoon. Hamish Leal, manager of the company’s boatyard on the outskirts of Falkirk, had welcomed us aboard the 58-foot centrally heated boat and shown us around Fiona’s comfortable cabins.

Now, after an early Sunday breakfast of bacon butties and hot tea, we’re following a sinuous route along the 240-foot contour that earned the Union Canal its nickname of ‘the mathematical river’. Just a couple of hours earlier, Fiona had nuzzled her way through the gates of the world’s only rotating boat lift – and, with 300 tonnes of water and steel suspended above our heads, I’d been hoping that the modern engineers had got their own sums right.

The Union Canal climbs rapidly from the Black Prince boatyard at its junction with the Forth & Clyde Canal. The early boatmen took several hours to work their way up the old Greenbank lock flight; but since 2002, when the iconic Falkirk Wheel boat lift replaced the long-derelict locks, boat crews have been making the climb in less than fifteen minutes.

There’s barely a sound as the Wheel’s massive steel arms begin to turn and, imperceptibly, everything around us starts to mutate. The sloping glass windows of the visitor centre slip sideways at first, then drop away as we’re lifted clear of the basin and a wide panorama opens up all around. Even Fiona herself seems to tilt sideways as we soar in a huge arc, with glimpses of the descending boats away to our left.

With the Wheel behind us we pushed on through open countryside, munching our lunchtime sandwiches on the after deck and gazing northwards to the distant Ochil Hills. But the bitter cold of early spring was slowly taking hold and, by teatime, we were grateful for the cheerful stove in Linlithgow Canal Centre’s waterside café.

The Centre’s volunteers are passionate about the canal and, over tea, Nuala Lonie told us about the charming Victorian-style launch moored outside. Derrick Hughes built Victoria at Braunston in 1972 and the Canal Society brought her to Linlithgow just six years later to run weekend pleasure trips during the summer. “Derrick came up here to see her once,” Nuala recalls. “But there’s a funny thing – the day that he died, Victoria’s propeller fell off!”

Next morning we motored on in bright spring sunshine, past the gaunt outline of Niddry Castle, where Mary, Queen of Scots sheltered before the fateful battle of Langside in 1568. Then, beyond the soaring Almond aqueduct, we kept a lunchtime appointment at Ratho.

Ronnie Rusack took over the Bridge Inn in 1971, and he’s been at Ratho ever since. “In those days the canal was just a dump,” he told us over a good roast lunch. Never one to shy away from a challenge, Ronnie soon began to wonder if using the canal might be the best way clean it all up.

First came the Bridge Inn’s own restaurant boat; then, Ronnie and the Reverend Hugh MacKay founded the Seagull Trust to provide free canal trips for disabled people. Initially based at Ratho, the charity now operates nine boats from its four Scottish bases. After launching the Trust, restoring the waterway was a natural progression. “We took the charity boats and put them elsewhere,” says Ronnie. “That helped us to raise money for restoring wee bits of canal”.

As the Millennium approached, Ronnie became involved in Britain’s largest, most ambitious canal restoration scheme. In just three short years, all 70 miles of derelict waterway between Glasgow and Edinburgh were restored; the project included the £20m Falkirk Wheel and over two miles of brand new canal. In 1999, Ronnie was awarded the MBE for his work with canal restoration and the Seagull Trust.

From Ratho it’s a short step into Edinburgh, with time for enjoying the long views to the landmark rail and road bridges striding across the Firth of Forth. Edinburgh’s tumultuous evening rush hour lay beneath us as Fiona drifted over the city bypass, where the new Scott Russell aqueduct pierces the city limits. In the golden evening sunshine we slipped quietly through Wester Hailes and tied up next to the green expanse of Harrison Park.

Thirty-six hours is far too little time in which to do justice to Edinburgh, but we made a brave attempt. Here, my wife joined Fiona’s company and we spent the morning exploring the 17th-century Writers’ Museum. Afterwards, a short bus ride to Leith was the prelude to an afternoon on board the former Royal Yacht Britannia, now permanently moored beside the Ocean Terminal shopping centre.

That evening we walked up to the Castle before relaxing in one of the Royal Mile’s many excellent restaurants. Next day, the crew split up to sample just a few of Edinburgh’s many attractions; the National Galleries of Scotland, Holyrood Park and the striking new Scottish Parliament. It was enough only to whet the appetite for more.

Up to eight million people use Scotland’s lowland canals each year. In and around Edinburgh the towpath bristles with walkers, joggers and cyclists; and, just down from our mooring, afternoon rowing clubs take over the waterway itself. We cast off before the deadline and turned Fiona westwards; by six o’clock, we had moored for the night in Ratho. After unwinding over a couple of pints of Deuchar’s at the Bridge Inn, it was time to stroll back to the boat for our supper.

Thursday dawned raw and damp, so we opted for a leisurely cooked breakfast before setting off. I took over the helm just west of the Almond aqueduct, under leaden skies that pelted Fiona’s coachroof with hailstones. But the weather cleared after a lunchtime stop at Port Buchan and we set off again in warm sunshine.

For the next few miles the canal winds through a landscape of rose-coloured shale ‘bings’. These ageing spoil heaps are the legacy of an enterprising Victorian chemist, James Young, who developed a way of extracting paraffin from the local shales. “Looks mighty like Ayers Rock to me,” said my wife in her best Aussie accent as Fiona chugged past one of the larger bings, rain-washed and gleaming in the afternoon sunshine.

We caught up with Mary, Queen of Scots once again at Linlithgow’s 15th-century Palace. Dramatically sited overlooking the loch, this was Mary’s birthplace in 1542. Now, the spectacular ruins huddle around a richly carved central fountain, and we explored the spiral staircases that lead up into a labyrinth of passages set deep within the Palace walls.

Later, our Royal progress continued beside the open fire in the dining room of the Four Marys; the pub was named after the ill-fated Queen’s ladies-in-waiting who, bizarrely, all shared the name Mary. Stone walls rise to the beamed ceiling and rich tapestries give the building a quintessentially Scottish atmosphere. We felt a world away from our own southern English roots as we sampled local fayre like Cullen Skink – a thick, creamy soup made from tasty smoked haddock and mashed potatoes.

The following morning, my wife and I walked back from an early supermarket trip to the tempting aroma of bacon drifting across the towpath from Fiona’s cabin. Setting off for our final day’s cruise, we crossed the Avon aqueduct, slipped through the Falkirk tunnel, and tied up within a stone’s throw of the Falkirk Wheel. There was one last treat in store.

In the depths of Rough Castle Tunnel, our outward journey had taken us beneath the Roman Empire’s most northerly frontier: the earthen banks and ramparts of the Antonine Wall. After more than 1800 years, it’s still possible to explore the Emperor’s forbidding banks and ditches, and a gravel path led us out across the heath to the site of Rough Castle Roman fort.

Back at the boat, we motored on through the tunnel in the wake of a fellow Black Prince boat; then, it’s straight out onto the Wheel, with fine views to the snow-capped hills north of Alloa. Half an hour later, Fiona was back on her mooring.

The Wheel had come full circle.

© David Foster 2006