Fenella is the sister of Basil, Baron Feldman of Frognal. But she doesn't have any title. Basil is a life peer as a reward for his political work.
Despite persistent published reports, Fenella Fielding was NOT the sister of actor Marty Feldman. The two are not related in any way.
Had to pay for her own ring in Carry on Screaming! (1966) which cost £9.