This rather rare 'Invincible' was produced under license by the Birmingham based Eagle Iron Foundry and sold through Alfred Brown & Co. builders' ironmongers, 81 Smallbrook Street, Birmingham. You can identify the partnership when viewing the brass cover plate.
A link to a picture of the Eagle Foundry (Paste in browser):
http://www.birmingham.gov.uk/cs/Satellite?c=Page&childpagename=Lib-Central-Archives-and-Heritage%2FPageLayout&cid=1223092759806&pagename=BCC%2FCommon%2FWrapper%2FInlineWrapper
A mention of A. Brown & Co (Paste in browser):
http://www.historywebsite.co.uk/Museum/locks/gazetteer/gazbb-z.htm