I am with the info above on Trusty Tractors, but to go back to Ransomes push mowers, all their hand push mowers never were cast with individual numbers, what Clive 1997 is referring to are Ransomes version of their truth about sales.
Anyone who has worked in sales in any industry or the lawn mower trade as I have will know, that round figures to the nearest thousand are circumspect.
To actually date these machines, there are two ways, firstly to define the introduction year, then to check for improvements made,via Patents. Secondly Ransomes changed its name on known certain years, which were cast into the lawn mower arms, eg Ransomes Sims & Head 1869 to 1881.
On hand machines it will always be difficult to define an end of production date, the year will be no problem with our dating records, but it has to be said that all Ransomes machines had spares available for up wards of 7 years after production, and we all know in the trade where machines were still being sold as new, after being stored by wholesalers by up to 5 years.