Some Colonial examples, first a photo of a New Zealand Railways L1 class wooden bodied open wagon underframe. The photo is borrowed from the Motorised Dandruff blog, about modelling NZR in 1:120 scale and well worth a look. I hope they don't mind. There were about 4000 L1 wagons built before 1900.
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Then a Victorian Railways H van, built 1893. They originally had a solid sliding door as well as the bar version on this one giving a choice of closed or ventilated van. Side and underneath views of the van at Echuca Wharf, which is not actually H9.
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The electrical conduit is not an original feature. The Victorian Railways were building all iron open wagons, as well as wooden opens with the same composite underframe as the H van through the 1890s. The 1850s Daniel Gooch designed iron vans and open wagons were still running at the time but there were several types of 1870s built all iron wagons which had proved to be not so durable.
Now to track down some UK examples.