Strangely enough, my current tapped keg is a Bulldog Pennine Peak Yorkshire Bitter and I'm finding it quite dark also.I have just done the 'Traditional Yorkshire Ale' from Worldwide Brewery Classics sourced via Hampsted Brewing. See photo, a single can kit. It's worked fine - dark brew - but personally I thought very little flavour and taste. However, it's a long time since i grew up drinking Tetley's in Yorkshire and maybe my tastes have moved on.
I'm hoping to get one of their Design A Brew Craft Packs, Cardinals ale in a month or two. @dowden87 has done one and says it's very Abbot like. That's a good thing as far as I'm concerned although I'm sure I'm in the minority with that.
Cheers Tom