Cannon cooker range

To my joy and delight, just about everything in the kitchen has broken down in the last 2 weeks so I went looking at cookers...

There seem to be quite a few Cannon cookers that are almost identical but vary greatly in price. The one and only difference between the Chester and Chichester is that the frame of the Chichester is padded out to make it 600mm whereas the Chester is only 535mm. The size of both the ovens and the rings are the same on both models. Is there any valid reason for the Chichester to be £180 more (in John Lewis)?

Also, the double oven seems a nice feature but are there any hidden catches? Is the combines oven/grill a nightmare to clean properly? And do the oven light bulbs last very long and cost a fortune to replace?

I don't know those models, but normally the larger oven is significantly smaller in a double oven unit than the oven in a single oven unit. You might want to consider if that suits your likely usage pattern. An alternative would be to go for a single full sized oven, and buy a microwave with convection and/or fan oven feature combined for rare occasions when you need two. This is what I have done. I typically use the microwave's fan oven for warming plates, as main oven is usually too hot for that when being used for cooking. The microwave's fan oven also occasionally gets used for conventional cooking if main oven is full (Christmas) or if I can't juggle multiple things to cook at same temperature in the main oven (and of course for things I prefer microwaved, like some vegetables).

Don't know those models (don't even know if they are gas/electric/ combined).

They last ages in my experience, providing you use the 300C temperature oven lamps. I put in a regular lamp once as I had it spare, and it only lasted a few days.