Top oven in my mothers Parkinson Cowan does not show any signs of life?

My father reported to me today that the Top Oven in their Freestanding, Parkinson Cowan Gas Double Oven, with eye level grill, seems not to have gas being supplied to it and as a result doesn't ignite. This oven, he says, is 20 inches wide and is quite an old model, my mother and father are 87 and 88 respectively, it is quite difficult explaining they may need a new oven. The rest of it works well. They did not seem to know what the model name or make was. Any suggestions?