All 3 Sutton boys grammar schools have non catchment places.
However, I would raise a note of caution before looking to move area. Such a move is not necessarily cheap, and must presumably cause a fair bit of disruption to family life. I would make sure that you have a good look at what local schools do with their high achievers before concluding that your child is better off relocating purely for a different type of school. There appears to be a greater need for schools to come together to reduce costs (indeed the Sutton girls grammars have just announced their proposed move to a MAT). All schools are tightening their belts, but Outer London schools in particular are hit, as teachers can work just a short distance away and get far more pay, and there is huge teacher shortage in key subjects. Schools are having to cope with changing demographics as well, and many of these schools have been forced to take in additional classes. There is increased uncertainty as to what any school will look like in 5-7 years time. For all we know, free schools and academies could even get the power to become academically selective. And there is now a huge focus on ensuring children make adequate progress, so your local schools will have to ensure that the bright year 7 attains the highest GCSE grades.
I wouldn't want to suggest that grammar schools won't continue to provide good or excellent attention to bright children. But given the cost, both financially and emotionally of moving, and that there must already be bright boys in your area, I would look carefully at what is on offer first. I get the impression that the educational landscape has changed a lot over the last couple of years, and will continue to do so over the next few.