Pretty sure that doesn’t make you British so much as “any living soul on Tumblr” today.
Pretty sure it’s British and V for Vendetta just used the poem and it’s a completely legit British celebration of the Houses of Parliament not getting blown up.
okay, okay, okay. British person here. It’s a legit poem, we learn when we’re young to remember bonfire night. The night when Guy Fawkes tried to blow up the houses of Parliament, but didn’t succeed. You can google or wiki it if you must.