I don't think that's quite the case. The first list almost certainly contains MO members, these can usually be identified by the renewal date of 31st August and the number sequence. A column headed "ECF Member" containing the value "true" or "false" is a bit of a give away. Presumably the office is required to maintain a list of Guarantors and it's an extract from this list which they have published.Howard Grist wrote: With regard to the membership list, the first worksheet - 'DMS All Categories' - contains a list of people who have paid money directly to the ECF for membership, and have mainly, but not always, signed the white form. The second worksheet - 'Reg Members' - is a list of members who have joined through a MO. As it happens, none of them seem to have signed the white form, but this is incidental to their inclusion on this list.
The DMS Members tab also contains the handful of Corporate Vice-Presidents. The names of CCF and Hastings Chess Club also feature.
What's missing is the membership category, this was deliberately withheld. You can however identify Family members from the multiple names with the same membership number and infer MOs from the renewal date and numeric sequence.
For what it's worth, the totals in each category are around 3050 in the first and 550 in the second. The total of active FIDE rated players is around 800. The count of 31st August renewals is around 1250. By no means all of these are MOs though.