It's the fact that there is no consistent evidence that makes understanding the market nigh impossible. We hear one thing, then another, then another, and trying to piece together an understanding is next to futile. But that doesn't matter as this isn't an important subject. No lives hang in the balance, and no-one's set to lose the livelihoods over PS4 outselling XB1 in the UK or XB1 outselling the PS4 in the UK. As a thought exercise and test of logic skills applied to vague data, it's a fun thread, but people should appreciate the limits of the discussion and how little can be known without hard facts and definite numbers.
With the data we have thus far, I'd say the ratio of PS4:XB1 in the UK is anywhere from between 9:8 and 3:1. Arguments can be made against either of those extremes, which is probably the limits of understanding of the UK market - what are the minimum and maximum possible ratios.
In the US and Japan, we get sales figures and actual ratios which is very convenient!