A Russell regular, the striking Antonia Ellis appeared in both Mahler (1974) and The Boy Friend (1971)
A very distinctive actress, her key attributes were legs that seemed to go on forever and a smile that broke across her distinctive strong features like sunshine through dark clouds.
Attributes which I think are shown well in these photos from each film.
As anti-semite Cosima Wagner in Mahler...
And as aspiring starlet Maisie in The Boy Friend...
Away from Ken, Antonia put her legs-and a good deal more-to good use in the Hywel Bennett sex comedy Percy (1971)
But she's probably still most famous as Lt Joan Harrington in the Gerry Anderson series UFO (1970)
A quick scoot on IMDB shows she hasn't done anything since 1979; as a 'party guest' the Dudley Moore US comedy '10' As a fan of Dud I like '10' but I can't quite recall her in it, but then it does sound like a fleeting appearance.
She seems to be a regular on the fan convention circuit these days.