I am preparing a monograph on the cast iron cannon preserved in the City of Derry in Northern Ireland. Two are Elizabethan, probably brought to the Lough Foyle Area by Sir Henry Docwra in the period 1600 - 1604. A further ten belong to the period ca. 1615 - 1635, and include four bearing the shield of the City of London. A group of seven are part of a consignment of 15 sent over by the London companies in the aftermath of the outbreak of the great rebellion of 1641. In 1641, the mayor of Londonderry wrote that Thomas Wentworth, Earl of Strafford had caused cannon to be removed from the City, probably in the summer of 1640. This was most likely due to his mustering of an army to fight in Scotland. I should be most grateful to anyone who knows of guns (most likely demi-culverins or sakers) bearing the London shield anywhere in Britain or Ireland and dating to the period ca. 1615 - 1635, as it is certain that guns were specially cast for the defence of Londonderry and Culmore Castle as part of the contribution of the Great Companies to the Plantation of Ulster. Best wishes Brian Scott