A panel attachment system for a gas turbine engine exhaust assembly comprising: a panel comprising: one fixed mount bracket; and at least one sliding mount bracket; and a casing comprising: one fixed mount boss; and at least one sliding mount boss; the or each sliding mount boss comprising: a fixed mount boss; and a locating tongue comprising a first end and a second end, the second end extending substantially parallel to the casing, wherein, in use, the fixed mount bracket is fixedly secured to the fixed mount boss, and characterised in that the first end of the locating tongue is connected to the fixed mount boss by a threaded fastener, and the second end of the locating tongue is slidingly engaged with a corresponding respective one of the or each sliding mount bracket, to thereby detachably connect the panel to the casing, such that any relative in-plane thermal expansion between the panel and the casing is accommodated by corresponding relative movement between the one or more sliding mount brackets and the corresponding one or more sliding mount bosses. a panel comprising: one fixed mount bracket; and at least one sliding mount bracket; and one fixed mount bracket; and at least one sliding mount bracket; and a casing comprising: one fixed mount boss; and at least one sliding mount boss; the or each sliding mount boss comprising: a fixed mount boss; and a locating tongue comprising a first end and a second end, the second end extending substantially parallel to the casing, wherein, in use, the fixed mount bracket is fixedly secured to the fixed mount boss, and characterised in that the first end of the locating tongue is connected to the fixed mount boss by a threaded fastener, and the second end of the locating tongue is slidingly engaged with a corresponding respective one of the or each sliding mount bracket, to thereby detachably connect the panel to the casing, such that any relative in-plane thermal expansion between the panel and the casing is accommodated by corresponding relative movement between the one or more sliding mount brackets and the corresponding one or more sliding mount bosses. one fixed mount boss; and at least one sliding mount boss; the or each sliding mount boss comprising: a fixed mount boss; and a locating tongue comprising a first end and a second end, the second end extending substantially parallel to the casing, wherein, in use, the fixed mount bracket is fixedly secured to the fixed mount boss, and characterised in that the first end of the locating tongue is connected to the fixed mount boss by a threaded fastener, and the second end of the locating tongue is slidingly engaged with a corresponding respective one of the or each sliding mount bracket, to thereby detachably connect the panel to the casing, such that any relative in-plane thermal expansion between the panel and the casing is accommodated by corresponding relative movement between the one or more sliding mount brackets and the corresponding one or more sliding mount bosses. a fixed mount boss; and a locating tongue comprising a first end and a second end, the second end extending substantially parallel to the casing, wherein, in use, the fixed mount bracket is fixedly secured to the fixed mount boss, and characterised in that the first end of the locating tongue is connected to the fixed mount boss by a threaded fastener, and the second end of the locating tongue is slidingly engaged with a corresponding respective one of the or each sliding mount bracket, to thereby detachably connect the panel to the casing, such that any relative in-plane thermal expansion between the panel and the casing is accommodated by corresponding relative movement between the one or more sliding mount brackets and the corresponding one or more sliding mount bosses.