Gibraltar-domiciled Armstrong has been quietly building a sizeable property portfolio during the past couple of decades. Mar Properties, the company in which he is a major shareholder, has just unveiled a 3m refurbishment to Blackpool Airport, in which it now has a 95% stake.

Mar acquired an initial shareholding in Blackpool Airport in 2004 as part of a consortium called City Hopper that paid 19m for both that and Wolverhampton airports. In the past fortnight, Mar Properties acquired all but a 5% stake held by Blackpool's local council.

Blackpool airport has been served by Ryanair for well over a year at this stage, something that has helped to boost passenger numbers. "When we purchased the airport 15 months ago, there were about 200,000 passengers going through it, " says 53year-old Armstrong. "We have that figure up to about 800,000 now."

It's a very "hands-on operation" for Mar now, Armstrong says. "We saw a big opportunity for business travellers to use Blackpool as opposed to opting for Manchester or Liverpool. It's also a low-cost base for carriers flying to Europe and that has worked well for us. There are about six routes to mainland Europe now and we hope to add about three more in coming months."

The airport is also an obvious property play for Armstrong, and he has sold nearly 50 acres in the past year. "There are about 500 acres around it, of which 100 acres were developed commercially, " he says "In the past year, we've been able to get land values up to about £300,000 ( 434,000) an acre, from about £70,000 when we bought it."

Because Mar didn't pay "an exorbitant price" for the airport, it is able to expand it easily, he says.

"We're going to have a five- to 10-year play on this to expand it. The airport is not quite profitable yet, but hopefully by the end of this year we will have it either neutral or making a profit."

In Northern Ireland, Mar Properties has become a high-profile commercial developer. Its investment in land throughout the 1980s and 1990s has given it some prime sites to exploit.

Among Mar's current joint projects is the 26storey, 65m Obel building, which will be home to a 144bedroom hotel and 186 apartments. Armstrong is also embarking on his first shopping centre development, Queen's Parade in Bangor. He has joined forces with boxer Barry McGuigan's former manager, Barney Eastwood, to build a 155m retail and commercial park in Newtownards, Co Down.

It is all a far cry from being ousted from northern Rhodesia, now Zambia, in the dark days of asset nationalisation and oppression under dictator Kenneth Kaunda.

Armstrong's father had been involved in the lucrative copper mining business before Northern Rhodesia declared independence in 1964. The family interests had grown to encompass a couple of hotels, retail units and a car showroom. Under Kaunda, the assets were taken into state control, with no compensation.

When he was just 13, Armstrong returned with his father to Northern Ireland, where they had retained some "small interests". Armstrong was keen to get involved.

"I didn't have the aptitude for school and I left when I was 15, " he said.

"Legally, I should have been there until I was 16, but they didn't come looking for me."

He worked initially in his father's hotel and pub businesses, before quickly moving on to making his own deals on behalf of the family. "The first deal I completed on my own was when I was 18, " he says. "I bought a house that had planning permission for additional units. It cost £4,700 and I sold it on later for a good profit."

Since then, the property game has known few boundaries for Armstrong.

Despite the troubled decades that were to follow his first deal, he continued to buy up land where others feared to tread. Along the way, his daughter, Danielle, joined the group.

"We dealt with all the trouble spots and became in tune with it, " Armstrong says. "It was normal to us.

We bought land that was hard to develop and sat on it for maybe 15 years. It was a real long-term investment."

Armstrong also ensures his assets will sweat.

"Under normal circumstances if you bought something for £50m, you'd be putting £15m into the deal, but if we buy a property for £50m, it has to be worth £65m, " he says. "So straight away, we have our £15m back. We don't buy off 4.5% or 5% yields just to look at organic growth. If there's not an automatic angle to it, we're not interested."

The UK property sector also continues to attract strong interest. Armstrong says Mar Properties was unable to buy anything in the first two months of this year because of the level of competition from buyers.

The UK property market remains robust, he says. "I think the prices being achieved at the moment are realistic and rents are still growing and I can't see any softening of the market."

Armstrong is also expanding his sights towards Canada and the US. "We've just done a big deal in Toronto, where we bought a £70m portfolio of apartments, " he said.

"A few weeks ago we bought a couple of office blocks and the yields on them are quite high, at about 9%. I might do a little more in North America next year. It's certainly a lot easier than back home."