This paper describes an analysis of data obtained from explosion experiments carried out as part of the CEC (Commission of the European Communities) collaborative project MERGE (Modelling and Experimental Research into Gas Explosions). Previously established theoretical ideas are extended to obtain a simple relationship between the flame position and the overpressure as a function of time. The observed overpressure measurements and this relationship are then used to calculate the flame position as a function of time. The results of the analysis are shown to be consistent with the measurements made in the experiments. The technique is then used to identify the contribution to the overpressure from individual terms such as obstacle drag. It is concluded that the observed behaviour can be interpreted satisfactorily by this simple method and further that the approach itself could be embodied in a predictive technique.