A mounting kit for fixing a trim panel to a body of a transport vehicle, in particular a rail vehicle, the mounting kit comprising: - a mounting sub-assembly, comprising: • a trim panel, intended to be attached to the body, preferably against or near the roof, and • at least one fixing device, wherein the fixing device comprises: - a fixing lug, configured to be fixed to the cladding panel, - a fixing flange, configured to be fixed to the body, and - a damping element, which connects the fixing lug to the fixing flange, the damping element being configured to limit the passage of vibrations between the fixing lug and the fixing flange, while the fixing flange is configured to be fixed to a fixing rail integral with the body, and the fixing lug of each fixing device is fixed to an edge of the trim panel, characterised in that the mounting kit comprises at least one holding bracket, each holding bracket comprising: - an assembly portion, configured to be assembled to a fixing rail in a reversible manner, preferably by hand and without tools, and - a support portion, configured to reversibly co-operate with the mounting sub-assembly when the assembly portion is assembled to the fixing rail, so as to hold each fixing flange in a mounting position facing a fixing rail, and in that the retaining bracket is configured to be removed from the fixing rail once the fixing flange is fixed to the facing fixing rail. - a mounting sub-assembly, comprising: • a trim panel, intended to be attached to the body, preferably against or near the roof, and • at least one fixing device, • a trim panel, intended to be attached to the body, preferably against or near the roof, and • at least one fixing device, wherein the fixing device comprises: - a fixing lug, configured to be fixed to the cladding panel, - a fixing flange, configured to be fixed to the body, and - a damping element, which connects the fixing lug to the fixing flange, the damping element being configured to limit the passage of vibrations between the fixing lug and the fixing flange, - a fixing lug, configured to be fixed to the cladding panel, - a fixing flange, configured to be fixed to the body, and - a damping element, which connects the fixing lug to the fixing flange, the damping element being configured to limit the passage of vibrations between the fixing lug and the fixing flange, while the fixing flange is configured to be fixed to a fixing rail integral with the body, and the fixing lug of each fixing device is fixed to an edge of the trim panel, characterised in that the mounting kit comprises at least one holding bracket, each holding bracket comprising: - an assembly portion, configured to be assembled to a fixing rail in a reversible manner, preferably by hand and without tools, and - a support portion, configured to reversibly co-operate with the mounting sub-assembly when the assembly portion is assembled to the fixing rail, so as to hold each fixing flange in a mounting position facing a fixing rail, - an assembly portion, configured to be assembled to a fixing rail in a reversible manner, preferably by hand and without tools, and - a support portion, configured to reversibly co-operate with the mounting sub-assembly when the assembly portion is assembled to the fixing rail, so as to hold each fixing flange in a mounting position facing a fixing rail, and in that the retaining bracket is configured to be removed from the fixing rail once the fixing flange is fixed to the facing fixing rail.