R.A.Butler, Britain's 56-year-old Home Secretary, and new chairman of the Conservative party, was filmed with his bride-to-be, Mrs. Mollie Courtauld, in London, October 15, the day following an announcement of their engagement.

Both have been married before, Mr. Butler has four children, Mrs. Courtauld has six. They have long been neighbours and friends.

Mr. Butler's wife, who died in 1954, and Mrs. Courtauld's husband, Polar explorer, Augustine courtauld, who died last March, were cousins and members of the wealthy Courtauld rayon-manufacturing family. Mrs. Butler inherited from her farther, Samuel Courtauld, art collector and philanthropist, a collection of valuable paintings, part of which - including works by Renoir, Cezanne, Seurat and Manet, - she bequeathed to her husband for life.

The welding, Mr. Butler told newsmen, would be a quiet one and would take place quite soon.