The sea green Dudson crockery (stoneware?) must have been produced in vast quantities for BR as you do occasionally see it second hand. Of course Dudson still exist as a major stoke based catering sector crockery manufacturer
https://dudson.com/
Pretty sure I have a BR marked tea set I picked up in a bric a brac shop some years ago. I also have one in a darker matt brown glaze that appears to be a higher quality in terms of its 'looks'
eg this sort of green tea pot
A vintage Dudson Brothers tea-for-one teapot for British Rail, 1970s. This chunky little teapot was produced for British Rail in the 1970s and is marked with a date of either 1973, 75 or 78. I believe
www.worthpoint.com
This sort of brown item
<p>3 Vintage BR British Railways Cream / Milk Jugs featuring the BR Double Arrow on their bases and made Dudson Brothers Pottery in the 1970s. </p><br><p>The larger jug is 7cm tall and the smaller jugs are 6.5cm tall. These items have a very nice function utilitarian feel to...
www.ebay.co.uk
Anyway - back in 1986 I worked for Travellers Fare in a Casey Jones outlet - aiming to emulate the McDonald's style fast food offer. Being 'fast food' all the products were served in disposable containers, and I think hot drinks were polystyrene cups, cold drinks waxed paper. We did have a seating area for eating in - it had been the TF buffet before conversion to Casey Jones.
Down in the cellar where we stored the disposable cups etc were supplies old green Dudson crockery no doubt from TF buffet days - some of this tended to end up in use in the staff rest room I think too.
Anyway - I well remember one day a chap coming in for a cup of tea and bemoaning the disposable polystyrene cups and saying he preferred to drink from 'proper crockery' given he was planning to sit in the restaurant area. We can't have been very busy at that particular moment, so I asked him to hang on, I nipped down to the cellar, got one of these old Dudson cups and saucers, washed it up, and served his tea in that. I recall he was slightly taken aback that I could achieve this in response to his complaint / request!