Hi Margaret ~ Gosh, it could be that the cat never tolerated being brushed, so the owners gave up and that is why he is so matted . . . I have an elderly girl (Lily, the blue in my avatar) with a medium length yet double coat, and I am constantly trying to keep up with her grooming because she is unable to reach all spots, and actually she has never seemed to be awfully fastidious in that respect anyway.

I would definitely try to inquire and maybe the owners could be convinced to allow their elderly "gentleman" a much-needed trip to the grooming salon. Depending upon the extent of the matting, the best option may be to simply shave him down. Severe mats can hamper a cat's ambulation, which may account for his sluggishness in getting around. Hope you can be of help to the sweet senior guy, and please keep us posted!