Any person who cannot stand safely for their journey and are elderly, pregnant, or have a disability can apply for a Priority Card
Successful applicants will be issued with a Priority Seating Card which can be shown to fellow passengers who are sitting in a priority seat. This will indicate that this passenger has been recognised by Great Northern or Thameslink as needing a priority seat. Card Holders will present their priority seat card and ask the person seated to give up their seat. However, consideration should also be given to their needs.
The Priority card does not guarantee a seat. Priority seats may already be occupied by other card holders or passengers with a similar need for a seat.
To travel in First Class accommodation you must have a valid First Class ticket. A Priority Seat card does not authorise you to sit in First Class. Priority seats in First Class Accommodation are for First Class ticket holders.
Renewal of cards is at the operators discretion but in general, cards will expire on a given date. For guidance, cards issued to pregnant ladies will expire two weeks after their due date. Applications for people with a temporary disability will expire two weeks after the expected date of recovery.
In order to qualify for the scheme you must be able to provide one of the following documents:
Copy of doctors note; Proof of Attendance Allowance; Proof of Disability Living Allowance; Proof of receipt of incapacity benefit; A letter from the Department of Work and Pensions; Copy of your certificate of Visual Impairment; Copy of your DB8 certificate; Copy of MATBI or Written confirmation of pregnancy
This information together with application should be sent to: FREEPOST RRBR-REEJ-KTKY, Great Northern and Thameslink Assisted Travel Service, PO Box 443 PLYMOUTH, PL4 6WP.
For more details and application form see this link