I don't know where in the UK you are, but there's a very good builders
merchants near me here in south London called Harris and Bailey.
They're a trade place but don't seem to mind dealing with the public.
They should either be able to source it or at least tell you who to
contact.

Harris & Bailey Ltd
50, Hastings Rd, Croydon, Surrey CR9 6BR
Tel: 020 8654 3181

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Seri