Blankett was born in approximately 1740 and by 1758 was a midshipman in the Royal Navy, serving in HMS Somerset at the Siege of Louisbourg and the capture of Quebec.

[1] In 1784 after the end of the war Blankett was recalled to service in command of HMS Thetis in the Mediterranean, receiving an honour from King Ferdinand of Sicily.

In 1798 he was given an independent command in Leopard, tasked with preventing the use of the Red Sea by the French, who had invaded Egypt earlier in the year under General Napoleon Bonaparte.

With growing bitterness he retained this uneventful command for three years, the presence of his force dissuading the French from pursuing operations in the region.

In 1801, his health broken by the heat and conditions in the Red Sea, he died on Leopard at Mocha on the Arabian Peninsula.