British arts in N.Y. - a welcome invasion

America may have won the war of independence over the British, but today, two centuries after the signing of the Treaty of Paris which officially ended the conflict, the British are ''invading'' again - this time with the largest arts festival they have ever held abroad.

The celebration, entitled ''Britain Salutes New York 1983,'' has mustered more than 200 separate events. Although it opened officially in New York last Thursday, many events will be opening this week and in May and June.

Sponsored by British and American companies that do business on both sides of the Atlantic, the (STR)2.3 million ($3.54 million) cultural extravaganza offers the United States a dazzling list of the best of British culture.

Among the visual arts events, there will be two exhibitions at the Metropolitan Museum: John Constable's paintings of rural England, through Sept. 4, and the more modern approach of Henry Moore's sculptures and drawings, from May 14 to Sept. 25. Also, Queen Elizabeth has lent her Faberge jewelry collection, which includes more than 200 works of art created by the 19 th-century Russian master craftsman Peter Carl Faberge, which will be on display at the Cooper-Hewitt Museum through July 10.

There's a variety of theater offerings, and coincidentally the eminent Royal Shakespeare Company staging of ''All's Well That Ends Well'' is at the Martin Beck Theatre.

The London Symphony Orchestra performs at Avery Fisher Hall, Lincoln Center, May 2 and 3, with the London Symphony Orchestra Brass Quintet giving a free concert at Rockefeller Center. Other musical groups from Britain - like the Edinburgh Quartet - are joined by local groups.

There's also a multitude of films, literary activities, and various other cultural events.

As for dance, the Royal Ballet Company is presenting a one-week season at the Metropolitan Opera House starting tomorrow (April 19), as part of a nine-week tour which will also take it to Japan, South Korea, Hong Kong, and China.

A new one-act ballet by Sir Frederick Ashton - ''Variations Capricci,'' with music by the late Sir William Walton and a setting by David Hockney - will receive its world premiere tomorrow.

Also included will be Ashton's dance version of Elgar's ''Enigma Variations, '' American choreographer Glen Tetley's ''Dances of Albion,'' and that enchanting pas de deux party piece ''Voices of Spring'' by Ashton, which bursts on stage in a flurry of rose-petal strewing and Russian-style effortless lifting.

Merle Park and Wayne Eagling, who created their roles, pour beauty, grace, and joy into the Strauss waltz, and audiences at Covent Garden love it. Kenneth MacMillan's historical ballet ''Mayerling'' premieres in New York April 22.

It tells the story of events leading up to the deaths of Crown Prince Rudolph of Austria-Hungary and his 17-year-old mistress, Mary Vetsera. The ballet has that unique MacMillan technique, and the two programs will give New York audiences an opportunity to see some of the great British dancers: David Wall, Lesley Collier, Marguerite Porter, Anthony Dowell, and Antoinette Sibley.

It will also introduce them to some of the promising stars-to-be: Alessandra Ferri, who has just been voted dancer of the year by readers of Britain's Dance and Dancers magazine; Bryony Brind, who was picked out by Rudolf Nureyev last year to accompany him in ''La Bayadere''; Karen Paisley; and Ravenna Tucker, to name but a few.

So the ''invasion'' is starting, and this time no one will end up the loser.