Roof tiles and fastening devices

A roof tile comprising an upper side and an under side, first and second lateral edges, first and second transverse edges, a downward-oriented flange running longitudinally along one lateral edge of said tile and a complementary upward-facing channel running longitudinally along the other lateral edge of said tile whereby a flange of one said tile will rest loosely in said channel of a second neighbouring said tile, a transverse groove running laterally along the upper side of said tile adjacent one transverse edge thereof and a complementary downward-facing ridge running transversely along the under side of said tile adjacent the other transverse edge thereof whereby said ridge of one tile will rest loosely in said groove of a second neighbouring tile, said tile being thereby adapted for interlocking engagement with laterally neighbouring tiles and overlapping engagement with longitudinally neighbouring tiles, said tile further comprising means for fastening said tile to a roof whereby said tile is provided with an aperture for receiving a resilient plug, said plug having a surface for bearing against said tile and being adapted to receive fastening means for fastening said plug to said roof and thereby resiliently fastening said tile to said roof.