Well actually this is nothing to do with William, but T Shakespeare an English maker who was producing concertinas from the 1890s to possibly the 1930s.
Here is a picture of a rare 30 Key C/G Anglo concertina, made in the late 1800s. It was fully restored by Dave Elliott, including new 6 fold bellows. Note the distinctive metal hand rests.
An experienced Anglo player reported that it had ‘the appearance and feel of a Jeffries and the sound of a Crabb’. There is a very good reason for this- it was probably made by T Shakespeare, who worked for both Jeffries and Crabb in the late 1800s. During this time he was acquiring parts from both companies and using them in his own workshop to produce what is estimated to be around 180 high quality concertinas. As this was a clandestine business his name was on very few of his concertinas, but he left several good clues behind.