The ensar was for many years the standard lens in ensign cameras, I have an Ensign Commando from 1948 with the ensar lens, uncoated, and stoped down it is no mean performer, but it can be prone to flare, The express lens seems to come into regular ensign use when Ross more or less took over the company, but certainly most pre war ensigns came with the ensar, which was,I think, produced in house by Houghton butcher, and I think is a triplet in design,
Richard