Around 1866/1867 the company merged with Peard and Jackson becoming Hart, Son, Peard & Co, therefore it is reasonable to assume any Robinson floor springs manufactured after this time would have Peard's name incorporated into the advertising.
https://en.wikipedia.org/wiki/Hart,_Son,_Peard_and_Co.
With the above information and the advertisement on the decor plate we are therefore able to work out that Steve and Sheila's Robinson floor spring must have been manufactured (and presumably installed) around 1865, certainly no later than 1867. Consequently this faithful device must have been controlling these doors for approximately one hundred and fifty three years and we now expect them to be doing the same for another hundred and fifty plus years.