Abstract: A lateral adaptor (6) for a main pipe (1), such as a structured wall plastics pipe consisting of a cylindrical shell (2) and a corrugated shell (3) bonded to the outside thereof, comprises a sleeve (7) with a flange (8) extending outwardly at one end and curved to match the internal curvature of the main pipe (1) and adapted at the other end (as by means of a socket (9) or a spigot, not illustrated) for connection of a branch pipe (not shown), an annular movable member (10) slidable on the sleeve (7) and having a curved face (11) to match the external curvature of the main pipe (1), an elastomeric seal ring (12) held captive between the to flange (8) on the sleeve (7) and the movable member (10) and having inner and outer curved faces (13, 14) to match the curvature of the flange (8) on the sleeve (7) and the face (11) of the movable member (10) respectively, an annular abutment member (15) adjacent the face (16) of the movable member (10) remote from its curved face (11), an annular shoulder (17) on the slee