Priscilla Buchan, Baroness Tweedsmuir British politician (1915-1978) (1915–1978) Parents Edythe Mary Unwin Alan Fortescue Thomson Children Priscilla Susan Buchan Joanna Catherine Grant Margaret Anne Grant Siblings Clare Frances Fortescue Thomson Partners John Buchan, 2nd Baron Tweedsmuir Sir Arthur Lindsay Grant of Monymush and Cullen, 11th Bt.