A seal assembly for a gas turbine engine comprising: a seal (69; 169; 269) including a main body (170; 270) extending circumferentially between opposed mate faces (178; 278), the main body (170; 270) including a sealing portion (177; 277) and an engagement portion (179; 279) extending outwardly from sealing portion (177; 277) along at least one of the mate faces (178; 278); and wherein the main body (170; 270) includes: a core (192; 292) including one or more core plies (CL) having a first fiber construction and arranged to establish an internal cavity ; an overwrap (194; 294) including one or more overwrap plies (OL) having a second fiber construction and arranged to follow a perimeter of the one or more core plies (CL) to establish the engagement portion (179; 279) and the sealing portion (177; 277), and the second fiber construction differing from the first fiber construction; and a platform insert (197; 297) extending between portions of the core (192; 292) and the overwrap (194; 294) to establish the sealing portion (177; 277), and the platform insert (197; 297) having a construction that differs from the first and second fiber construction; characterised in that the one or more core plies (CL) are triaxially braided and the one or more overwrap plies (OL) are biaxially braided, and wherein the first fiber construction comprises substantially continuous fibers and wherein the second fiber construction comprises substantially continuous fibers. a seal (69; 169; 269) including a main body (170; 270) extending circumferentially between opposed mate faces (178; 278), the main body (170; 270) including a sealing portion (177; 277) and an engagement portion (179; 279) extending outwardly from sealing portion (177; 277) along at least one of the mate faces (178; 278); and wherein the main body (170; 270) includes: a core (192; 292) including one or more core plies (CL) having a first fiber construction and arranged to establish an internal cavity ; an overwrap (194; 294) including one or more overwrap plies (OL) having a second fiber construction and arranged to follow a perimeter of the one or more core plies (CL) to establish the engagement portion (179; 279) and the sealing portion (177; 277), and the second fiber construction differing from the first fiber construction; and a platform insert (197; 297) extending between portions of the core (192; 292) and the overwrap (194; 294) to establish the sealing portion (177; 277), and the platform insert (197; 297) having a construction that differs from the first and second fiber construction; characterised in that the one or more core plies (CL) are triaxially braided and the one or more overwrap plies (OL) are biaxially braided, and wherein the first fiber construction comprises substantially continuous fibers and wherein the second fiber construction comprises substantially continuous fibers. a core (192; 292) including one or more core plies (CL) having a first fiber construction and arranged to establish an internal cavity ; an overwrap (194; 294) including one or more overwrap plies (OL) having a second fiber construction and arranged to follow a perimeter of the one or more core plies (CL) to establish the engagement portion (179; 279) and the sealing portion (177; 277), and the second fiber construction differing from the first fiber construction; and a platform insert (197; 297) extending between portions of the core (192; 292) and the overwrap (194; 294) to establish the sealing portion (177; 277), and the platform insert (197; 297) having a construction that differs from the first and second fiber construction; characterised in that the one or more core plies (CL) are triaxially braided and the one or more overwrap plies (OL) are biaxially braided, and wherein the first fiber construction comprises substantially continuous fibers and wherein the second fiber construction comprises substantially continuous fibers. <EOS>