I saw one very similar in a garden centre today also, priced at £8.99, would agree with everybody else most likely poland or china. These are still on ebay sold as whitefriars which drives ya bonkers.
They are at nearly every car boot sale in the country in a varity of colours and quality seems to range from very poor to reasonable lower end glass.
I think you will be waiting for quite some time to get a positive country of origin on these, its also highly likely that more than one country make them.
michelle