Paul,
Now I've got home here are the details:
Order Number: 6868
Progressive Number(works no.)2817/1887
Interestingly the first 3 Lancashire & Yorkshire locos (wks. 2823-2825) are under the same order number.
I was wrong about the L&YR examples being built with saddle tanks - these were added c1901. The L&YR built another 5 to the original design. I have an interesting chapter in a book, including drawings and photographs (locos and stock) - I can copy it for you of you are sufficiently interested.
G