" IF you do not understand French, you did not miss t n Ahing. " says one " IF you do not understand French, you did not miss t n Ahing. " says one of the four slim Frenchmen in Les Freres Jacques (Adelphi) after the gabbled introdui:tory chorus to an evening of '.song and dance " sketches. But as the evening danced along. many in the audience realised they were missing quite a lot. Although the antics of the f rb'es Jacques are very amusing, their songs, nearly all in French, cannot alevays be fully appreciated by an audience not conversant with the French language. which is a pity. because there's a story behind every song, often a moral. Nevertheless, one doesn't have to know French to revel in some of the mimes of these French artistes. Wearing black tights. coloured bodices, white gloves. they are like puppets dangling on an elastic band: legs waggling. hips wriggling, arms wafting-and all with the greatest of ease. In song, they blend with a harmony reminiscent of Les cornpagnons de fa chanson, which is some achievement considering they are invariably tumbling about the stage at the same time.