A stay in place lining for lining a structure of concrete or other curable construction material comprising: a plurality of panels connectable in edge to edge relation via complementary connector components on their longitudinal edges to define at least a portion of a perimeter of the lining; wherein each panel comprises a first connector component comprising a protrusion on a first longitudinal edge thereof and a second connector component comprising a receptacle on a second longitudinal edge thereof, each edge-to-edge connection comprising the protrusion of the first panel extended into the receptacle of the second panel ; the protrusion comprising a generally straight stem extending from a base of the protrusion and a barb extending from the stem and toward the base of the protrusion as it extends away from the stem ; the receptacle comprising a catch extending into the receptacle and positioned to engage the barb when the protrusion is extended into the receptacle , the engagement of the barb and the catch retaining the connector components in a locked configuration; wherein the protrusion extends into the receptacle in a direction generally parallel to transverse edges of the panels, the transverse edges generally orthogonal to the longitudinal edges; wherein for each panel , the first connector component is offset from a plane of a body of that panel ; characterized in that for each panel , the first connector component comprises a concavity that opens in a direction that the stem extends from the base of the protrusion and the second connector component comprises a finger shaped to be complementary to the concavity, the finger extending into the concavity and forming a finger lock when the edge-to-edge connection is made; and wherein for each panel, the finger is offset from an exterior plane of the panel and the finger is fully engaged in the concavity when the edge-to-edge connection is made. a plurality of panels connectable in edge to edge relation via complementary connector components on their longitudinal edges to define at least a portion of a perimeter of the lining; wherein each panel comprises a first connector component comprising a protrusion on a first longitudinal edge thereof and a second connector component comprising a receptacle on a second longitudinal edge thereof, each edge-to-edge connection comprising the protrusion of the first panel extended into the receptacle of the second panel ; the protrusion comprising a generally straight stem extending from a base of the protrusion and a barb extending from the stem and toward the base of the protrusion as it extends away from the stem ; the receptacle comprising a catch extending into the receptacle and positioned to engage the barb when the protrusion is extended into the receptacle , the engagement of the barb and the catch retaining the connector components in a locked configuration; wherein the protrusion extends into the receptacle in a direction generally parallel to transverse edges of the panels, the transverse edges generally orthogonal to the longitudinal edges; wherein for each panel , the first connector component is offset from a plane of a body of that panel ; characterized in that for each panel , the first connector component comprises a concavity that opens in a direction that the stem extends from the base of the protrusion and the second connector component comprises a finger shaped to be complementary to the concavity, the finger extending into the concavity and forming a finger lock when the edge-to-edge connection is made; and wherein for each panel, the finger is offset from an exterior plane of the panel and the finger is fully engaged in the concavity when the edge-to-edge connection is made. <EOS>