Coat of arms of the Stewart family and the 1st Marquess of Londonderry. This forms a part of the more recent arms of the Vane-Tempest-Stewart Marquesses of Londonderry (the full armorial can be seen here: www.europeanheraldry.org/united-kingdom/families/families-s/house-stewart-vane-tempest/).
This vector image includes elements that have been taken or adapted from this file:
Tinynanorobots