Every Plaid Cymru MP on record, current and former. Affiliation is shown as a period rather than a present-tense fact, so an entry from a past term is not re-attributed under someone's current status.
Dates are party-membership dates, taken from Parliament's published party history for each member, and are not the date someone was elected. A member who crossed the floor is listed under each party they sat for, with each period dated, and their entries are filed under whichever party they sat for on the day.
Each entry says whether the member was elected for the party or defected to it mid-term, drawn from Parliament's record by comparing when the affiliation began against when the seat did. How periods are derived.
No sitting Plaid Cymru MPs recorded. The member list fills on the first ingest.
No former members recorded.
Every sitting MP's party history is checked on each ingest, so a member who leaves the party is picked up and their period closed. An MP who left the Commons altogether before this record began would not be.