A slightly boring topic but, after ages searching, I found my perfect pair of black skinny jeans yesterday so thought I would share.
these
They are £85 but Whistles currently have 25% off with a Grazia voucher until 18th March making them £63.75.
They are extremely stretchy, skinny all the way down to the ankle, a very dense black colour and very comfortable. They are reasonably high waisted (I am paranoid about the risk of showing underpants, or even worse a builder's bum with low rise jeans!).
In my opinion they compare very well to the much more expensive premium denim brands I have tried/bought previously. Hope this helps someone else who has been searching!