The prince reigned for 71 years, from 1858 to 1929, making him one of the longest reigning monarchs in history.
Unfortunately the photo’s not on display at the moment, but it is among 75,000 images that you can purchase on the fantastic National Portrait Gallery website.
For more details visit the National Portrait Gallery’s online shop.
Do you know of more Liechtenstein culture in London? Tell us about it in the comments below.