The device in colour on the oak background is identical with the School Badge and the seal of the East Sussex County Council. It consists of a shield with four quarter-ings and combines the arms of the County with those of the Feudal Lords of the Rapes of Lewes, Pevensey, and Hastings, the three ancient divisions of East Sussex.
The first Quartering, the Sussex Arms, shows Six Golden Martlets (birds with very small feet and no claws) on a blue ground. It may be seen in the large stained-glass window at the end of Westminster Hall, and is the heraldic device of the ancient Kingdom of the South Saxons.
In the second Quarter, the Arms of the Earls de Warrenne are taken, being gold and blue check. For the third, the Arms of De Aquila are used. He came from L'Aigle in Normandy and, in allusion to the name of his native town, bore on a blue ground a spread Eagle of gold. Hence the Rape of Pevensey was called the "Honour of the Eagle," and the ancient Seal of Seaford is "an Eagle displayed."
The fourth Quarter is the Cinque Port Arms of three demi-lions conjoined to hulks of ships. This was adopted because Hastings Rape contains not only the premier Port but also Bulverhythe and the ports of Rye and Winchelsea. The Arms are formed on the dexter side by the golden lions of England on a red ground, and the sinister side of the shield bears argent halves of ships on a blue ground, in allusion to the obligation of these ports to provide ships for the Royal Navy.
(Most of the above information was extracted from the Sussex Daily News of May, 1889, and was supplied by the courtesy of Mr. J. B. Hadlow, the designer of the School Shield).
School Chronicle 1931
The first reference I have found to the school motto is in Miss Vobes' introduction to the first School Chronicle in 1929. It comes from St Paul's Epistle to the Galatians 5:13. The full verse is:
For, brethren, ye have been called unto liberty; only use not liberty for an occasion to the flesh, but by love serve one another.
Janet Pope