Canton is in Ordinaries.
Canton. A small rectangle in the top left corner.
Fox. Ermine, on a chevron azure three fox's heads and necks erased or on a canton of the second a fleur de lys of the third. The canton is an augmentation of honour to his paternal arms, granted out of the Royal Arms as a mark of esteem to him and his heirs forever, by King Charles II following the Restoration of the Monarchy. Source.
Churchill. Sable a lion rampant argent a canton of the last a cross gules. Source.
Lionel Plantagenet 1st Duke Clarence 1338 1368.
England Edward III a label three points argent canton gules. Source.
Spencer Churchill. Quartered 1&4
Churchill a canton of St George, 2&3
Despencer a bend sable three escallops, overall an escutcheon St George overall an escutcheon
Capet.