Yes, it is an elm. It is English elm, Ulmus procera.
It is similar in some respects to the Wych elm (Ulmus glabra) but U. procera has fewer pairs of main veins on the leaf (10-12 versus ~17 pairs) and longer petioles (5mm versus 2-5mm). There are other factors, too.
Other elms found in the UK but rejected by me: Uu. laevis, americana, carpinifolia, x hollandica, pumila, parvifolia.