"What's the difference between Royal Oak membership and the Heritage Pass, and which one should I purchase?"

• The Royal Oak Membership is annually renewable 
  (Individual $55; Dual $80; or Family $90)

Royal Oak members are entitled to free admission to most National Trust properties open to the public in England, Wales, Northern Ireland and Scotland (totaling over 450 properties and sites.)

• The Heritage Pass is a short-term pass that is valid for
  4 days ($74 per person; $149 per family)
  7 days ($100 per person; $204 per family)
  15 days ($128 per person; $263 per family) 
  30 days ($171 per person; $359 per family)
  Note: Family covers 2 adults and 3 children 15 years and under

The Heritage Pass entitles you to free admission to National Trust properties as well as many other historic sites (almost 600 sites in total.)

For more information and to purchase the Great British Heritage Pass, click here.