Adam’s designs for enlarging Knowsley comprised a U-shaped building, retaining the earlier range (as seen on the plan (Adam volume 33/72), and adding a mirroring range, with a new central block between the two. The scheme was far too ambitious for Lord Derby’s purse and was not executed (see scheme notes).

Like Adam’s various designs for The Oaks, Lord Derby’s other country house in Surrey, this scheme combines an interesting mixture of castle style elements such as crenellations, towers and slit windows, with classical elements such as an oculus, Venetian and tripartite windows, an arcade and colonnades.