Lawrence considered that the current tenders were too slow. They were full displacement hulled craft unsuitable for responding quickly. He had become associated with Hubert Scott-Paine whose company, Supermarine, designed the Schneider Trophy winning aircraft in 1922. Scott-Paine had also employed a young designer, Reginald Mitchell of Spitfire fame. As I understand it the Purdy Biscayne Baby speedboat was used as a tender to one of the support boats for the Schneider Trophy. Apparently the engine needed attention and Lawrence offered to rebuild the engine, setting about restoring and tweaking the boat at the same time. Perhaps the idea for the fast boats came from this. Lawrence and Scott-Paine worked together and Lawrence did much of the sea trials. Scott-Paine's British Power Boat Company at Hythe on the Isle of Wight, was eventually to go on and design many high speed rescue and attack speedboats for the Navy and RAF used in WW2.
As can be seen Lawrence's involvement from the beginning to where he got to before he retired was the production of the RAF's ST 200 seaplane tenders, which he was justly proud.
In January 1935 in a letter to John Buchan he writes:
That for eight years, and now for the last four I have been so curiously fortunate as to share in a little revolution we have made in boat design. People have thought we were at finality there, for since 1850 ships have merely got bigger. When I went into R.A.F. boats in 1929, every type was an Admiralty design. All were round-bottomed, derived from the first hollow tree, with only a fin, called a keel, to delay their rolling about and over. They progressed by pushing their own bulk of water aside. Now (1935) not one type of R.A.F. boat in production is naval... We have found, chosen, selected or derived our own sorts: they have (power for power) three times the speed of their predecessors, less weight, less cost, more room, more safety, more seaworthiness. As their speed increases, they rise out of the water and run over its face. They cannot roll, nor pitch, having no pendulum nor period, but a subtly modelled planning bottom and sharp edges.
Now I do not claim to have made these boats. They have grown out of joint experience, skill and imaginations of many men. But I can (secretly) feel that they owe to me their opportunity and their acceptance. The pundits met them with a fierce hostility: all the R.A.F. sailors, and all the Navy, said that they would break, sink, wear out, be unmanageable. To-day we are advising the War Office in refitting the coast defences entirely with boats of our model, and the Admiralty has specified them for the modernised battleships: while the Germans, Chinese, Spanish and Portuguese Governments have adopted them! In inventing them we have had to make new engines, new auxiliaries, use new timbers, new metals, new materials. It has been five years of intense and co-ordinated progress. Nothing now hinders the application of our design to big ships - except the conservatism of man, of course. Patience. It cannot be stopped now.
For those interested in the development of these boats, in 2021 there is to be a book published by John Johnson Allen which will document Lawrence's involvement in the fast boat project.