This week’s postcard is a rather dramatic image depicting a 9.2 inch coastal defence gun:

Looking at the uniforms of the gunnners, this image was taken between the wars. However the Mk IX and X 9.2 inch guns were to see service with the British Empire from 1899 to 1956 and Portugal were to retain them until 1998.
The Mk IX was designed as a coast defence gun, with a three-motion breech. Only fourteen were built and the Mk X, introduced in 1900, incorporated a single-motion breech and changed rifling, succeeded them. 284 of the Mark X version were built by Vickers, of which 28 examples are known to survive today, all except one fitted on barbette mounts. One in Cape Town is on a disappearing mount.
These were ‘counter-bombardment’ guns designed to defeat ships up to heavy cruisers armed with 8-inch guns. They were deployed in the fixed defences of major defended ports throughout the British Empire until the 1950s.
Their role was to defeat enemy ships attacking the ships in a port, including warships, alongside or at anchor in the port. However, where guns covered narrows, such as the Dover Straits, the Straits of Gibraltar, or the Narrows of Bermuda, they also had a wider role of engaging enemy ships passing through the straits. Normally deployed in batteries of two or three guns, a few major ports had several batteries positioned miles apart.