As always the aim was to get the best I could for a minimal budget. Mandarin stone do a rectangular grey riven slate tile for £22/m2 which is amazing value. Luckily the month I needed to order, it was Stone of the Month and so I got an additional 25% discount!!!
The slate is 600 x 100, which wasn't quite the look I wanted so we cut the slates in half and continued with more herringbone... poor Stewart (see Bathroom installation for more herringbone tiling).
As usual, contrary to most peoples mistake I have ended up with loads of extra tiles again, which I'm struggling to find a use for!