The Hutton may have started it all on the British side. He did nto call his watches hald chronometers but rather "Patent Lever Chronometers". From what I can tell cause a furor.
He showed then at the Great London exposition.
This one was probably purchased as a result of it being exhibited.
This watch passed through 5 generations.
Its escapement has been replaced with a Swiss club tooth wheel with rasied tips, a simpel table roller and American adjustable banking.
It has a long history.
I have a copy of Lawrence's transmittal letter to Vinton. It states that he. Lawrence was so impressed by Huttons description of careful adjustment that he sent the watch in its unopened box and asked Vinton to get it engraved, which the cuvette shows he did.
I believe it was sold directly to Amos Lawrence on the advice and help of his uncle who was the US ambassador to England and probably saw it at the Great Exposition. Hutton got a gold medal for these.
All the great makers were in London so I imagine Hutton's patent lever and precision levers was discussed among them.
Bond, his US distributor, was not pleased with this sale and probaly the idea of a lever watch as a chronometer, and arranged to have Hutton hauled in to a law office to sign a promise not to sell directly to Americans.
Later Bond sold one of these to the US Army to survey the Gadsten purchase. Bond listed it as a Hutton's best lever, no use of chronometer.
I got my 1855 date from reading the Lund obit but it is a recollection from years ago.
English Half chronometers are earlier than Swiss half chronometers and had even less official definition but were different. Until the advent of Kew testing they were the best English lever watches. Not so for Swiss demi chronometres.
There were also patent union chronometers with used a form of Robin escapement and they were usually marked as Union chronometers and are the subject of a David Penney monograph.
Except for Admiralty tests for marine chronometers, the English did not do rating of watches until 1885
I got my date from the Lund Obit and 1855 was what I inferred from the bio information. I belvei it started gradually.
As to lever versus detent;
Earnshaw wrote that an Emory watch had bee trialed by teh Board of Longitude under the influence of Count Bruhl. He was very upset since he regarede Emory as Swiss with no business being in London be evidently his detent chronometers were enough better than they did not buy the Emory.
When Neuchatel tested watches the rated them and compared escapements. By the 1870's the levr was doing better than pivoted detent chronometers and was very close to spring detents. This may have been distorted because many they testged were marine chronometers, a larger timepiece. Even with these, the differences were very small. Tihs was 70 + years after the introduction of spring detents and the lver had a lot of development by then.