I cleaned a range last week it was an old Rangemaster 110 which the lady said she had had for 12 years. The old Rangemaster's are branded Leisure and this model was the 'Victoria' and are they usually white but internally they are exactly the same as the Rangemaster 110. So normally this would be a reasonably easy job as most of the panels are self cleaning. I usually do a quick dip on these and all the grease, however greasy they are, comes straight off. The effect at the end is a brand new cooker.
This one was very dirty! The grease in the main oven was about 3 inches thick and was layered with old burnt chips and dog hairs. So in all it took me about 3 hours to do which is about 30 minutes more than normal but it looked great at the end.
Whilst I was cleaning it the lady kept asking me "Is this the dirtiest oven you have ever seen?". This is a common question and I told her that it wasn't as I had the one which had been covered in dog hair all over on the outside like a fur coat. But it was certainly a dirty one.
I often get the person who says "it was the previous owner who did all that". On one occasion I asked "how long have you been here then?" She replied "18 years" !!Google+