Here are my pictures taken at Tilbury Fort on Monday. They include an interesting series of pictures of a British Spigot Mortar. The mounts were large reinforced concrete blocks with a metal pin in the top. These were so massive and robust that many remain in position to this day, although I expect most people don't realise what they are. The example at Tilbury Fort actually has a rare mounted example of the mortar, also known as a Blacker Bombard.
The first Bombards appeared in late 1941 and were positioned around airfields, important road junctions and in coastal positions and were predominantly manned by the Home Guard although they were issued to regular units as well. By mid 1942 over 22,000 had been produced and issued to forces throughout the country. However they were never a popular weapon, possibly because they were only effective at close range leaving crews vulnerable both to counter-attack and shrapnel from their own projectiles!