Under managing director Tom Lamb, Henshaw has for the past 15 years been Scotland's leading creator of the defining architectural feature of all flagship commercial and headquarters developments - the glass facade or skin of the building.
London's Marriott Hotel in Kensington, whose atrium has the biggest single glass panel in Europe, and the Harvey Nichols facade in Edinburgh are typical of the top drawer, high-quality projects carried out by Henshaw, which has had Sir Angus Grossart as mentor and shareholder for the past 35 years and Mr Lamb at the helm for 31.
That makes Mr Lamb a valuable independent voice among the UK development industry's hard-pressed sub-contractors, and he pulls no punches in calling for a "culture change in the industry", to stop a race to the bottom in contract pricing and the creation of a generation of shoddy, even dangerous, buildings.
"Over the past couple of years there have been massive problems in the construction industry, huge job losses, lack of work, and a hell of a lot of expertise and skill has gone out of the industry," the veteran says.
"As far as I'm concerned it's been a depression not a recession, and this time round the industry has lost the plot, off the back of demands from clients who I think, frankly, have been badly advised. The end result is we are building crap."
Mr Lamb says main contractors "are demanding lower and lower prices", getting a dozen or more prices from sub-contractors then "taking the lowest price and demanding 10% off it, which a route to disaster".
He adds: "There has been a big casualty list, and we now find our competition is coming out of London." Some of the sub-contractors who subsequently vanished, he says, "were just waiting to get their affairs in order before walking away".
The 58-year-old boss has no stake in the business, but says: "I am allowed to run the business, it's my baby."
The firm was founded in 1904 by metalworking artist Charles Henshaw, who came to Edinburgh from Birmingham, and whose three sons established the firm as a leader in decorative metalworking.
Its foundry in Russell Road, Gorgie, cast the bronze lamp standards surrounding Eros in Piccadilly Circus, the Versailles-style chandelier in the Archers Hall in Edinburgh, fittings for Floors Castle, and later the Cafe Royal pub sign in the capital.
On leaving school in 1973 Mr Lamb joined as a draughtsman for his first five-year stint at the firm. It was "a Dickensian place to work", still in the Henshaw family and about to hit financial difficulties. Noble Grossart stepped in as an investor and ended up in control of the company, Sir Angus still holding a significant stake today alongside his friend and majority shareholder John Lambie. Mr Lamb returned to the business in 1982, after a stint with a go-ahead glazing company, on condition that he could set up an aluminium systems division.
He was soon given full control of the business, the new division was profitable from the outset, and the historic operations were wound down and eventually closed.
"The company has been transformed over that period," Mr Lamb says. "It was basically doing some architectural metalwork, had a small foundry, was losing money, and turning over £500,000." Metalworkers took 10 years to train up, but would then be lured to the oil industry. "I was allowed to rationalise the business, there was a lot of resistance but I ensured nobody lost their job."
Turnover before the crash had climbed to £19m, but it plunged to £12.5m before recovering and should hit £14m this year.
"We were flexible enough in our overheads and our costs that we could make adjustments... shareholders have taken no dividend through this period. We are keeping the business in the black, we are ticking over at the moment and just about making a profit. We were making £1m pre-tax, which was very satisfactory at the time, and much of it was invested back into the business."
Henshaw sets a limit on turnover, because it will only use its established teams of experienced high-quality installers.
Mr Lamb says: "As we moved into recession, one of the messages that came from Sir Angus was my mission was to bring us through with Henshaw's reputation intact - I thought that was a great message."
One frustration for Mr Lamb has been the overseas takeover of the firm's raw material supply, which is largely controlled by Nippon of Japan, new owner of Lancashire's Pilkington.
He says: "The UK has sold its soul to foreign investment and we have no control over our manufacturing - a good example is glass. Decisions are being made in Tokyo, not St Helens. They have been closing down plants in the UK, much of it to force up demand and create price increases." He says glass previously sourced in the UK now comes from France, Germany and Austria, while Nippon had warned that Pilkington was under scrutiny for its profitability.
Mr Lamb also believes the government has, until recently, neglected the importance of construction. "The industry has changed dramatically, it has been absolutely hammered. The government keeps going on about the manufacturing industry, without actually focusing on the construction industry which is a huge driver of the economy."
But at Henshaw, in its original headquarters where decorative metalwork and chandeliers grace the corridors, the resilient Mr Lamb is confident of a return to growth and profitability, the firm's reputation intact.
"It has been tough going for the past four years. Six months ago I still remained pretty pessimistic, economic indicators were not good in the country, but there is definitely some wriggle-room now. I am far more optimistic."