I do not know very much about the boats' history yet. However I found some things on a few yacht brokers' homepages and in old books and magazines. (Many thanks to Craig Anderson of the Old Twin Keeler Newsletter and Simon Harrison from the UK who provided me with a lot of material).
I am still looking for more information though, so if you know something interesting, please tell me.
The Alacrity 19 was designed in 1960 by Peter Stephenson. It was an open plan, relatively beamy yacht and they were built by Hurley Marine for the
Essex based Hurley agent Russell Marine Ltd. They performed well but the accommodation and headroom was limited.
The Alacrity was marketed as a Hurley for one year - 1969. Hurley did not just mould the hulls for Russell Marine but completed the whole yacht ready to take to sea. Russell Marine built them alone after about 1972.
I don't know how many boats were built, but it is more than 1000.
The design was based on an original plywood design, although adapted to fiberglass later and made a bit longer (18'6'' instead of 17'3''). There is still a lot of wood in the interior of the boat.
Apparently the hull for the plywood version was made in the same factory and using the same processes as the Mosquito bomber of WW2 which was an all-wood aircraft.
There are several versions of the boat: The Mk1, MkII, and the weekender which seems to be an MkII with a slightly different cabin layout.
Additionally there is a model called Alacrity 670 (or Catalina 22 in the USA). This boat is not based on the same design.
There are also some similarities between the Alacrity and the Vivacity 20, drawn by Desmond Pollard. The Vivacity 20 basically is a somewhat longer and heavier version of the Alacrity.
The Alacrity 19 is sometimes also referred to as Alacrity 18.