"If two records had a similar name and the same date of birth, or a similar name and exactly the same postcode, then they were considered a match. Important: Companies House data only publicly provides the month of birth - not the day. In a general population that would not be reliable for matching identities because there is a high probability that two people with the same name are born in the same month and year. However, given company directors represent a significant sub-section of the population, we felt that this matching would be acceptable for a public showcase."
So in the (much much much more common) case of all the directors called John Smith, rather than the directors called David Robert Joseph Beckham, just how reliable is this assumption?