Complex sentence: English historian K.B. McFarlane estimated Stafford's total potential income to have been £6,300 gross annually, at its peak between 1447 and 1448, although the centrepiece of Buckingham's estates, and his own caput, was Stafford Castle.
Split into simpler sentences: English historian K.B. McFarlane estimated Stafford's total potential income from his estates to have been £6,300 gross annually, at its peak between 1447 and 1448. The centrepiece of Buckingham's estates, and his own caput, was Stafford Castle.