I live in Essex very close to the M25. A 25 mile journey, particularly if it involves the M25, can take simply ages. The London area is extremely congested most times of day and a 52 mile round trip could be arduous. To be frank it would make far more sense for your brother to be closer to your mother if at all possible. It may well be that you are right and he may not choose to visit much, but if you insist on having mum somewhere more convenient for yourself, you run the risk of making that a self fulfilling prophesy.