"Fans voted from a total of 16 kit designs, but this was by far the most popular. I really wanted to make something that marked the importance of the sacrifice of those who fought against fascism.
"We have always been known as fans who do not accept racism, sexism and homophobia, so it made total sense. We didn't expect our tiny club to be noticed by Spanish football fans but we're delighted nonetheless."
The club said the shirt design was a tribute to the International Brigades, paramilitary units set up by the Communist International, a group who fought against fascism in Spain during the civil war in the 1930s – which was made up of volunteers across Europe, including the UK.
It features a slogan 'no pasaran' on the back, meaning 'they shall not pass' – which was used by the Republican troops at the time.
The tiny fan-owned club has been struggling to keep up with demand, with the club saying it crashed their website and forced them to charge a higher rate of tax on all purchases.
Clapton – who said they gained 20 new members from Spain, bringing their total to over 400 – beat Wanderers FC 5-2 on Saturday while wearing the new kit.