A gas turbine engine comprising: a section (60; 160) including an array of blades rotatable about a longitudinal axis, an array of vanes (64; 164) adjacent to the array of blades, and an array of blade outer air seals (63; 163) arranged circumferentially about the array of blades relative to the longitudinal axis; and a seal assembly (70; 170; 370; 470) dimensioned to span between the array of vanes (64; 164) and the array of blade outer air seals (63; 163), the seal assembly (70; 170; 370; 470) comprising: a first side plate (172; 372; 472), a second side plate (174; 374; 474) and a backing plate (176; 276; 376; 476) that extend circumferentially about the longitudinal axis; a first brush seal (178; 378; 478) between the first side plate (172; 372; 472) and the backing plate (176; 276; 376; 476); a second brush seal (180; 380; 480) between the second side plate (174; 374; 474) and the backing plate (176; 276; 376; 476); and wherein the first brush seal (178; 378; 478) is dimensioned to establish a first sealing relationship with the array of vanes (64; 164), and the second brush seal (180; 380; 480) is dimensioned to establish a second sealing relationship with the array of blade outer air seals (63; 163), characterised in that the first and second brush seals (178, 180; 378, 380; 478, 480) extend radially inward from a radially inner periphery (182; 282) of the backing plate (176; 276; 376; 476) to establish the first and second sealing relationships. a section (60; 160) including an array of blades rotatable about a longitudinal axis, an array of vanes (64; 164) adjacent to the array of blades, and an array of blade outer air seals (63; 163) arranged circumferentially about the array of blades relative to the longitudinal axis; and a seal assembly (70; 170; 370; 470) dimensioned to span between the array of vanes (64; 164) and the array of blade outer air seals (63; 163), the seal assembly (70; 170; 370; 470) comprising: a first side plate (172; 372; 472), a second side plate (174; 374; 474) and a backing plate (176; 276; 376; 476) that extend circumferentially about the longitudinal axis; a first brush seal (178; 378; 478) between the first side plate (172; 372; 472) and the backing plate (176; 276; 376; 476); a second brush seal (180; 380; 480) between the second side plate (174; 374; 474) and the backing plate (176; 276; 376; 476); and wherein the first brush seal (178; 378; 478) is dimensioned to establish a first sealing relationship with the array of vanes (64; 164), and the second brush seal (180; 380; 480) is dimensioned to establish a second sealing relationship with the array of blade outer air seals (63; 163), characterised in that the first and second brush seals (178, 180; 378, 380; 478, 480) extend radially inward from a radially inner periphery (182; 282) of the backing plate (176; 276; 376; 476) to establish the first and second sealing relationships. a first side plate (172; 372; 472), a second side plate (174; 374; 474) and a backing plate (176; 276; 376; 476) that extend circumferentially about the longitudinal axis; a first brush seal (178; 378; 478) between the first side plate (172; 372; 472) and the backing plate (176; 276; 376; 476); a second brush seal (180; 380; 480) between the second side plate (174; 374; 474) and the backing plate (176; 276; 376; 476); and wherein the first brush seal (178; 378; 478) is dimensioned to establish a first sealing relationship with the array of vanes (64; 164), and the second brush seal (180; 380; 480) is dimensioned to establish a second sealing relationship with the array of blade outer air seals (63; 163), characterised in that the first and second brush seals (178, 180; 378, 380; 478, 480) extend radially inward from a radially inner periphery (182; 282) of the backing plate (176; 276; 376; 476) to establish the first and second sealing relationships.