Gumtree Manager interview questions

I was headhunted by a recruitment agency and agreed to interview at Gumtree in their Richmond office in London. Having worked for a similar company and position, I thought my background would make me a great fit. The interview itself was quite formal with typical interview style questions. The interview lasted about an hour in which a rapport was established and a couple of jokes were even shared. I was disappointed to be informed that although, Gumtree thought I had the right experience and came across as a down to earth candidate. They decided not to proceed ahead with my application as they felt that I would not be a "CULTURAL FIT" for the company. You can imagine my shock. This can be interpreted in many ways and may even be interpreted as discrimination. I can’t seem to shake off the feeling that my gender and/or my race had something to do with the decision. It might be best for candidates to apply elsewhere with a more professional hiring process where their experience and personality are evaluated. Just an fyi, base salary at Gumtree appears to be quite low in comparison to average salaries in London