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. <EOS>