Ken, I don't think Ray is suggesting that but a question about Cooper's T58 has arisen on The Nostalgia Forum.

Jim raced the Bowmaker Cooper T55 in early 1963 - indeed racing it initially on his 21st birthday in the NZGP (the first at Pukekohe) and although the car was offered to the Palmers, the decision was made to buy the Hyslop T53 because it was a known quantity.