Incorporation date question

Hello again,

I am reviewing the incorporation dates of companies in the live snapshot and I noticed two dates have a disproportionate number of incorporations that do not match the daily trends of months around them. On 01/01/1900 there were 1,838 and on 01/01/1981 there were 4,680. I reviewed the documents in the file history of a handful of companies and it looks like those might not be the actual incorporation dates, I am curious if this is simply an issue of the digitisation of historic records or if it was assigned as the default value at some point? Thanks!

So sorry for such a delay in responding, but I have still not got a definitive answer.
What I have so far is:-

  1. it is known about
  2. a significant number of these are non standard corporate body types (Assurance Companies/Registered Societies/Royal Charter Companies) where they do not incorporate with us but we just hold their details on file. The incorporation date then seems to be some form of default.
  3. we should not be outputting an incorporation date for registered companies hence our links to the mutuals register e.g. BIGGAR BREWING CO-OPERATIVE LIMITED overview - Find and update company information - GOV.UK
    I am still trying to find out more info.
    Hope that helps for now.