In some ways I think that Jamie is an ideal partner for Jonny. Jamie has boundless energy and enthusiasm but isn't quite up there as a "big name" which I think is perfect for Jonny who is a quiet guy who likes to play with partners who have a bit more court presence but who are not a "big name" that puts too much pressure on him. From what I have seen, and what others have said, the problem with the Jonny and Colin (Fleming) partnership was that they are both the "quiet man" of the team.
For avoidance of doubt I both assume and hope that this is a one off and that Jamie will be continuing his successful partnership with John Peers.