Metal-framed beds really came into their own in the late 19th century, when bed makers put out the message that metal framed beds were the answer to termite issues, which were an issue in the UK at that time. As you would expect, these metal-framed beds were very well made and that means many are still around.
If you are looking to acquire such an item, here are a few tips to determine the age of the frame.
Art Deco or Art Nouveau beds were made in the late 18th or early 19th century, while Victorian styles preceded that. If you would like some comparisons, a Google image search should produce results. French designs tend to be more artistic, while English and Scandinavian frames are generally sturdier, with more of a practical approach.
The Victorians mainly used cast iron to make metal bed frames, and if the frame is made from aluminium, then it is a reproduction, which may have been made pre-WWII, as aluminium was popular then. There are genuine antique beds for sale from UK dealers who can easily be located with an online search, whether you prefer an Edwardian brass bed or an iron single bed, all styles can be found at an established antique dealer.
If the frame uses brackets, it is likely a reproduction, as earlier versions used hitches rather than brackets to attach headboards and footers. Also, antique double beds are the same size as a modern King or Queen size bed, which is worth noting.
Many metal bed makers stamped the frame, which might be a brand name, a lot number or simply a date, so do examine the frame thoroughly. If you buy from an established antique dealer, they would know a lot about the history of the piece and would no doubt be able to tell you who made it and when. If you would like some further reading on how to determine the age of a metal bed, there are articles you can find online that share useful tips.
If your knowledge of antique beds is rather limited, you are advised to seek out a local antique dealer and tell him what you are looking for. The UK antique dealers are all networking, so it is quite easy to source a specific piece, and if you have a few images, even better! A Google search will bring up all the local antique dealers and over a few weeks, you can pay them all a visit and get acquainted, setting the scene for future assistance.
If you are looking at a bed and are unsure of its origin, take a few images on your smartphone and send them to your local antique dealer, who can likely tell you more about the item. Appraisal services are always on offer by the antique dealer, who does a lot more than simply selling antique furniture.