Representatives of the Smith Institute and Transport for London were in Inverness this week.

They were there to gather local views on how well or badly the Highlands are connected to London in terms of air services.

The Smith Institute should not be confused with the Adam Smith Institute. They are two very different animals. The latter, named after the Scottish moral philosopher and a pioneer of political economy, works to promote libertarian and free market ideas.

The one with surname only, describes itself as a leading independent 'think tank' which promotes progressive policies for a fairer society. The London-based body was founded in memory of the late John Smith, the Scottish MP who was the former leader of the Labour Party and of course a proud son of Argyll.

According to the Smith Institute: "With the economy returning to growth the policy discussion is now focusing on how the UK can build a balanced and lasting recovery across the whole country. A key component of this objective is regional connectivity, not least air travel. However, the number of flights from the regions to the UK's hub airport has been in steady decline for a number of years - as Heathrow has suffered from ever more severe capacity constraints.

"In its interim report, the Airports Commission makes clear that this has contributed to a continuing decline in UK connectivity, with negative effects on jobs and growth. The regions are not only affected by the lack of UK city to city connectivity, but also by poor links to the London hub for their access to global markets. Failure to address the reduction of these links could have serious and lasting economic repercussions."

The key element in this whole debate is what happens in London.

The Airports Commission is analysing the need for additional airport capacity and has shortlisted three options, which include adding a third runway at Heathrow, lengthening an existing runway there, and a new runway at Gatwick. But it will also consider a new airport in the Isle of Grain in Kent.

A study by York Aviation and Oxford Economics published last month concluded that a third runway at Heathrow would "do little to improve regional connectivity" and that a new four-runway hub on the Isle of Grain in Kent, was required.

The researchers estimated that additional connectivity brought about through the so-called "Boris island" option - favoured by the Mayor of London - would deliver economic benefit to Edinburgh of £451million in Gross Value Added (GVA), along with 2,590 new jobs by 2050. Glasgow would gain around 2,620 new jobs and £358m in additional GVA.

The report states that without any new airport capacity in the south-east, Edinburgh would lose nine daily flights. If Heathrow added a third runway, Edinburgh would still lose four daily flights to London, however.

In contrast, creating a new hub would result in 20 more flights per day between Scotland and London than there would be under a third runway at Heathrow; Edinburgh Airport would have five more; Aberdeen two more, and; Glasgow three more, according to the report.

The Airports Commission is due to report in a year's time and the Smith Institute believes that places like the Highlands and Islands and other regions of the UK must be considered by the commission. According to the York/Oxford study: "An Inverness service is not expected to be operating to Heathrow by 2050 with either No Expansion of capacity or even with a Heathrow Third Runway. By 2050, the constraint dynamic in both cases will be such that the small aircraft needed to operate services from relatively small markets, such as those around Inverness, will be priced out in favour of more revenue intensive uses for the slot .

"However, with a Four Runway Hub ,we forecast that a four times daily service using a 100 seat aircraft would be a viable proposition. By 2050, this service might handle around 250,000 passengers per annum.

"The viability of other hub services from Inverness is not expected to be significantly affected. Given the isolated geographic position of Inverness and the limited alternatives in terms of existing hub services, it is not surprising that the route offers significant economic benefits.

"By 2050, it is estimated that total economic benefits to passengers and the airport of around £32.9 million per annum will be delivered in and around Inverness, compared to No Expansion or with a Heathrow Third Runway.

"In terms of the impact in the wider economy, the additional business travel generated by the route would support around £66 million of GVA and 850 jobs by 2050. This represents a 0.8% increase in GVA by 2050. This would be distributed across a range of sectors."

So if these calculations are accurate, it would appear a no-brainer for Inverness, which has had a very unsettling record of retaining services to London.

As it happens Flybe launches its new service to London City airport in September. But last year the same company announced it was selling the slots for its Inverness flights to Gatwick airport to EasyJet for £20m. In fact EasyJet has maintained the Gatwick as well as its Luton link, much to the relief of the civic and business leaders in the north.

They suffered a huge blow in 1997 when British Airways pulled out of its three-times-a-day service to Heathrow, leaving British Regional Airlines to operate a service to Gatwick with smaller planes.

The Heathrow link was re-instated in 2004, with BMI offering daily flights, however the service was discontinued in March 2008, the airline citing rising costs at Heathrow as the reason.

Inverness in itself acts as a mini hub with the likes of the Western Isles in particular relying on services to the Highland capital and perhaps Orkney, although Shetland to a lesser extent. This may just be a useful argument with the Airports Commission given the huge importance of Europe in the control of the international airways.

The Lisbon Treaty of 2007 committed the European Union to try to reduce disparities between the levels of development of the various regions. It specifically cites "demographic handicaps such as the northernmost regions with very low population density and island, cross-border and mountain regions". So connections to main airport hubs should be key to that.

In truth many in the Highlands and Islands are just happy that there still are connection to London (Gatwick, Luton and soon to be City) although not to Heathrow. A secure link to wherever the UK's main hub is, regardless of the vote in September, remains the dream.

Given that the Western Isles have still to get rid of significant sections of single track in the main road spine down the archipelago, it puts the airport debate into some kind of Highland context.