Instead of buying a full price pair of blue Leigh Jeans, I decided to I buy these jeans for £15 in the Topshop sale and dye them blue:
I looked for a pair of jeans that were quite light in colour and already had dark blue, black or brown stitching. The stitches are made from polyester and therefore can't be dyed to a different colour so if you want the jeans to look like you bought them blue check the stitching on the outside and the inside (because the inside may peek through to the outside). The inside of these jeans use pink thread but it doesn't show through so I was good to go!
I bought the dye from John Lewis for about £5. The process is easy, the packet dye (rather than the box) comes with the salt and dye already combined and you don't have to do so many washes to rinse out the machine afterwards. I just popped the jeans and dye into the washing machine, used 2 normal spin cycles and I was done.
The colour is more of a grey-blue rather than a jeans blue, but I'm still pretty happy with the results. Because of the two washes, the jeans can come out of the machine feeling a little stiff initially but after a few wears they do soften up and go back to normal. So all in all a new pair of Topshop Leigh Jeans for £20!