Langrex is hardly a secret: http://www.langrex.co.uk/
Incidentally, Langrex (http://stores.ebay.co.uk/LANGREX) and Colomor (http://stores.ebay.co.uk/COLOMOR-VALVES-TUBES-COMPONENTS) are located in the same village (Billingshurst) on opposite sides of the railway line.
I had a littl ebit sour experinece with Langrex once. I bought a pair of Mullard ECC33 from them. After I sold them a frined from the forum let me know that those tubes were not Mullard but Tungsram.
When I question Langrex they told me they were Mullard "export" tubes. Not after a lot more questioning and pressure they came out clean and accept they were really Tungsram.
Fortunatley they agreed to take them back and refund me.