All you need to do now is to get the bricks to match the older ones. Relatively easily achieved by having a bucket of water with some thin earth mixed in to make very slightly muddied water. Just paint on and instant weathered bricks. If you make the mix with only enough earth to just colour the water you can get the effect and if not enough add some more earth, let dry between applcations to see how the effect is working.
Another more severe brick color changing effect is to use Cow Dung instead of earth, this will attract algee and give some green to the bricks in time. Yogurt or milk has a similar effect and is probably more SWMBO friendly!
Finally for a rusting effect on stone, bricks or footpaths is to use Sulphate of Iron (used to feed Azelia's) this will give a realy nice change of colour and can be made more or less severe by just using more or less of the stuff. A spray with water and overnight the effect is magical.
