In 1714, he succeeded his father as Lord Aston of Forfar in the peerage of Scotland.
She died in 1723 during the birth of their 11th child, James, who would succeed him as Lord Aston of Forfar.
Two daughters also reached adult life: Margaret, who became a nun, and Catherine, who married Edward Weld of Lulworth Castle, Dorset.
The Astons, like the Howards, were staunch Roman Catholics: during the outbreak of anti-Catholic hysteria called the Popish Plot, Walter's father and uncle had been charged with treason and imprisoned in the Tower of London, although they were never brought to trial, and in due course were simply released.
The 4th Lord Aston commissioned a painting of himself, his wife, and seven of their children by Richard van Bleeck.