MANY aviation anniversaries are being celebrated this year. 1996 is not only the 60th anniversary of the Supermarine Spitfire and Bristol Blenheim but it is also the 50th anniversary of Heathrow Airport, the 30th anniversary of Glasgow's Abbotsinch Airport and the 80th anniversary of the previous Glasgow Airport at Renfrew.

Many people do not know that there used to be an airport at Renfrew. This is hardly surprising as the site has been completely redeveloped with the M8 motorway at Hillington passing close to the old runway, and Tesco occupying the site of the terminal building.

Some of the earliest flying experiments in Scotland were carried out in this Moorpark area of Renfrew, just before the First World War and in 1916 the Ministry of Munitions established an airfield there.

After the First World War, civil aviation took off in Britain and scheduled airline services were operating from Renfrew by the early thirties. The Scottish Flying Club established a base there and in 1934 they constructed some hangars and a large clubhouse with built-in control tower which later served as Renfrew's terminal building until a new one opened in 1954.

Renfrew Airport played a key role in the Allied war effort between 1939 and 1945. In the spring of 1942, a large number of Spitfires landed there en route to Malta. At this point in the war the fall of this strategically important Mediterranean island seemed inevitable. A small force of RAF fighters - mainly obsolete Hurricane IIs - were holding off a vast number of German and Italian aircraft including the very latest Messerschmitt Bf 109Fs and Gs.

In April, 1942, 47 Spitfires were flown to Renfrew and transported by road to Greenock where they were loaded on to the USS Wasp, the US Navy's large aircraft carrier, which then sailed to a flying-off point in the Western Mediterranean. This first shipment arrived in Malta on April 20, but most of the Spitfires were subsequently destroyed in Axis air raids on the Maltese airfields. Another batch followed in early May - again using Renfrew and the Wasp - and this time the carrier took on her precious cargo at the King George V Docks near the airfield.

On May 9, 1942, Wasp flew off her 47 Spitfires from a point 650 miles west of Malta. Another 16 aircraft were launched from the Royal Navy carrier HMS Eagle which then returned to Gibraltar to take on a further 16 Malta-bound Spitfires.

Historians agree that these 79 Spitfires turned the tide of the air battle over Malta and saved the island, thereby paving the way for Allied victory in North Africa and Europe. So, in its own way, Glasgow's tiny airport at Renfrew played an important role in the defeat of Hitler.

Soon after the relief of Malta, Renfrew was chosen as a base for the assembly and testing of American aircraft which did not have the range for such flights and so had been shipped across the Atlantic.

Renfrew Airport was ideally placed to receive these aircraft as it lay close to the docks. In 1942 contractors carried out extensive building work to improve its facilities. Two concrete runways - one 6000ft long and the other 4020ft - were laid down and additional hangars, workshops, and hardstandings were constructed.

After the war Renfrew reopened as a civil airport but it retained a dual military and civil role well into the fifties. A new and distinctive terminal building and control tower were built in 1954 and facilities were improved.

However the days of Renfrew were numbered as it was too small to cope with the anticipated increase in air traffic. The runway was too short for most jet aircraft and even the propeller-driven Vickers Vanguards - which were operated by British European Airways (BEA) on the Glasgow-London run in the early sixties - could not operate easily from such a cramped site.

During the fifties there was considerable debate about where Glasgow's airport should be situated. Interestingly, the controversy continues to this day. One option was to develop Prestwick Airport which had a 10,000ft runway, was relatively fog-free, and had plenty of space for expansion. Unfortunately Prestwick lost out because it was too far from Glasgow and lacked fast rail and road links with the city; the same reasons why it lost its transatlantic gateway status in 1990.

An expansion of Renfrew was also discounted because of lack of space and a proposal to scrap both Glasgow and Edinburgh airports and build a new super-airport halfway between them - perhaps near Falkirk - was deemed too radical and expensive.

Although the Macmillan Government favoured Prestwick they bowed to local pressure and in 1960 they agreed to the development of an existing military airfield at Abbotsinch, near Paisley, which was then used as a Royal Naval Air Station, HMS Sanderling. Like Renfrew, Abbotsinch also had a long and distinguished history. As early as the First World War the site was used for the construction of airships, including the R34 which crossed the Atlantic in 1919.

In 1932, a military airfield was established at Abbotsinch and this became the headquarters of the local Auxiliary Air Force Squadron No 602 (City of Glasgow) Squadron which operated Spitfires with great distinction during the Second World War. In 1943, the airfield was transferred to the Fleet Air Arm and it became an important base for the maintenance of naval aircraft and training for air crews.

In 1963 HMS Sanderling closed to allow construction work to begin on the new airport. A supermarine Attacker aircraft which had been mounted on a pedestal by the gate on the Red Smithy road, and had become a well-known landmark, was removed and placed in storage. It can now be seen in the Fleet Air Arm Museum in Yeovilton, Somerset.

The new airport took nearly three years to build and did not open until May, 1966. The first aircraft to land on the runway was a BEA Handley-Page Herald, call sign Whisky Bravo, which touched down at 6.21pm on May 1, having left Renfrew six minutes before. The next morning Abbotsinch opened for business at about the same time as the very last flight out of Renfrew - a BEA Vickers Vanguard bound for London - took off.

Since then Glasgow Airport has expanded many times. For some years its development was restricted by a Government ruling which allowed only Prestwick to operate flights from Scotland to North America. The rescinding of this decision in 1990 resulted in a massive expansion of facilities at Glasgow. The original 1966 terminal was cleverly enlarged and modernised at a cost of #52m and apron space and car-parking facilities were expanded.

One possible obstacle to further development is the runway. A 2000ft extension was built in 1973 to increase it to 8720ft which is long enough to handle every type of aircraft. However, this is still not enough to allow a wide-bodied jet with maximum fuel and passenger load to take off from Glasgow. This means direct flights from Glasgow to some North American destinations are not possible.

A further extension would be needed to make this possible and this would involve a costly realignment of the M8 motorway and the Paisley-Greenock railway line. Such alterations can be expensive; a mere 800ft extension at Manchester Airport in 1981 - involving the diversion of a river - cost #8.6m.

Regardless of whether the runway is extended or not, the future of Glasgow Airport looks bright as passenger traffic is set to grow. As for the old Renfrew Airport, little remains to remind the traveller of this important part of Scotland's aviation heritage apart from a small cairn which was built at the junctions of Newmains and Sandy roads to commemorate the crew of an air ambulance flight who lost their lives on a mission to Islay in 1957.

Renfrew's distinctive terminal building survived well into the seventies and could be seen from the M8 motorway. In 1977 plans were drawn up to convert this unique building into a shopping and leisure complex. Unfortunately nothing came of this and the old terminal was demolished in 1978 to make way for redevelopment of the site.

As motorists speed past the Hillington Rolls-Royce factory on their way to Glasgow Airport, they should reflect that they are passing through an area which played a great role in the development of aviation and the history of the Second World War.