Orchestras mean different things in different places. And they come into existence in a variety of ways. In the Republic of Ireland, the National Symphony Orchestra and RTE Concert Orchestra were established to fulfil broadcasting needs. The Boston Symphony Orchestra was founded - and for a long time funded - by a visionary individual, Henry Lee Higginson. Many a US orchestra has been brought into being as a gesture of civic pride, funded out of the private pockets of interested musical citizens.

In Europe, the funding tends to be public, though it was private money which enabled Thomas Beecham to launch the London Philharmonic Orchestra in the 1930s and the Royal Philharmonic a decade later. Perhaps the strangest origin is that of the London Symphony Orchestra, set up in 1904 by musicians rebelling against the conductor of the Proms, Henry Wood, for insisting that players hired for a concert should turn up for rehearsals and concerts they were booked for, rather than take last-minute lucrative offers themselves and fob the Proms off with deputies.

Belfast's orchestral history in the 20th century ranges widely. It includes the extension of a 19th-century tradition, through the amateur/semi-professional orchestra of the Belfast Philharmonic Society. There was an early broadcasting orchestra, known at various times as the Belfast Wireless Orchestra, the BBC Northern Ireland Symphony Orchestra, which gave concerts under men as eminent as Elgar and Vaughan Williams; sadly, it had to be disbanded after the outbreak of war in 1939. After the war, there was a BBC Northern Ireland Light Orchestra and also a City of Belfast Orchestra.

The municipal orchestra used to call on BBC players for its concerts, and it was a BBC decision to stop this practice which actually led to the formation of the Ulster Orchestra. The crisis provoked by the BBC was resolved when the Arts Council of Northern Ireland intervened and decided to set up its own orchestra. And the orchestra was very much its own, administered by ACNI from 1966 until 1980, when the BBC, yet again, precipitated major change.

It was actually the BBC which brought about the creation of the Ulster Orchestra as we know it today. For all its generosity as a patron of the arts, the BBC has long had problems with the burden of financing the orchestras it supports. In the late 1970s it set about disbanding a number of its orchestras. But resistance was fierce, resulting in the famous disruption of a musicians' strike in 1980. Some of the BBC orchestras were rescued, but the BBC Northern Ireland Orchestra was not among them. Well, not directly. With the co-operation of ACNI, 18 players from the BBC orchestra were merged into an expanded Ulster Orchestra, which was then finally set as a self-governing organisation.

The funding structure represented a four-way partnership, with money coming from ACNI, the BBC, the Gallaher tobacco company, and Belfast City Council.

The orchestra was fortunate at the time to have Bryden Thomson as its conductor. He was a charismatic presence in the concert hall, and his pioneering recordings of Hamilton Harty on the Chandos label helped put the orchestra on the international map. The orchestra made its debut at the Proms in London in 1985 (it's been back regularly since) and made its first European tour in 1986 (including an appearance at the Musikverein in Vienna).

Artistically, the Thomson years represented a peak in the orchestra's achievement. And the arrival of Yan Pascal Tortelier in 1989 marked another high, with a notable concentration on French repertoire, both in the concert hall and on disc. It was widely hoped that Tortelier would extend his three-year term. But he was made an offer he couldn't refuse by the BBC Philharmonic in Manchester, an orchestra with the resources to explore an altogether larger and more rewarding repertoire.

UNFORTUNATELY, with the departure of Tortelier, the Chandos recording activity ceased. The term of En Shao, who was wellliked by Ulster audiences, was musically lacklustre, and unravelled the achievements of Tortelier in building an orchestra with a distinctive suavity and polish to its playing. And there were no commercial recordings made in those years either.

Dmitry Sitkovetsky, who followed in 1996, pursues a double career as a violinist and conductor. What I've heard of his work in concert has been patchy, but he's used his contacts in the musical world and astute assessments of other performers and conductors greatly to the orchestra's advantage.

When Sitkovetsky steps down at the end of the next season, he will be followed by another performer-turned-conductor, the Swiss ex-flautist, Thierry Fischer. Fischer's work with the orchestra so far has been extremely impressive across a broad range of periods and styles.

On any number of fronts, the orchestra faces ongoing challenges. The opening of the Waterfront Hall in 1997, with its greatly expanded capacity, is one that has been more than successfully met. It has to be a matter of wonder that the Ulster Orchestra in Belfast can regularly fill a hall more than twice the size of the NSO's home base in Dublin. But the orchestra is still heard to best advantage in the altogether warmer acoustic of the Ulster Hall.

"Crisis" is a word that features regularly in discussions of the orchestra's funding. The overall budget for the financial year which ended in 1999 was £2.77 million sterling, of which ACNI contributed 43 per cent, the BBC 21 per cent, box office 11 per cent, sponsorship 9 per cent, and Belfast City Council 4.5 per cent. ACNI's grant, currently £1.3 million sterling has been frozen for next year, at a time when British legislation is forcing the withdrawal of Gallaher's sponsorship of nearly £65,000 sterling. So the crisis is not likely to pass in the short term.

As a high-cost, high-art institution, the Ulster Orchestra is seen by some community activists as an obvious target for robbing Peter to pay Paul.

However, the orchestra's educational work in West Belfast has been of a quality to win it a Royal Philharmonic Society award. Looking further ahead, Belfast, through its City Council, has declared an interest in being nominated as European City of Culture in 2008.

Given the international impact of success in this endeavour, it would hardly be a smart move now to do anything other than nurture what is, after all, Belfast's most famous cultural institution.

The Ulster Orchestra plays a programme of Elgar, Mendelssohn and Dvorak under its principal guest conductor, Takuo Yuasa, at St Canice's Cathedral, Kilkenny, on Saturday, August 12th at 8 p.m. And Dmitry Sitkovetsky's other orchestra, the New European Strings Chamber Orchestra, are at St Canice's on Wednesday 16th at 8 p.m., when Sitkovetsky is soloist and director in a programme of Bach, Mendelssohn and Schubert.