You've got a point there actually - it was only the shirt and the socks. The home shirts would have been fine that day - but the shirts weren't allowed to clash at all.
It was a ludicrous situation, but I don't think it was down to the referee alone. I think the Prem regs differ slightly from the FL, I don't think any part of the kit is allowed to clash at all in the PL, and our home shorts and socks were black, same as Newcastle's. In the FL they don't seem as stressed. At the Bristol game this year, both keepers were in the same kit. (Would have been fun if one of them had gone up for a last minute corner)
I'm surprised we weren't stopped from using that kit from the off. The grey kit was officially called charcoal I seem to remember, which is a shade of black - and our home kit was entirely black apart from three amber stripes.