He was last seen around 12.40am today – New Year’s Eve.
Police are growing increasingly concerned for his welfare and issued an appeal for information.
He is described as white, 6ft 5in, slim, with ginger hair. Harry, from Watford, is believed to be wearing a khaki jacket, grey tracksuit bottoms and dark trainers.
Officers are growing increasingly concerned for his welfare.
If you have information, you can report this by calling 999 immediately if you are with Harry now or have seen him in the last few moments.
You can report information online at www.herts.police.uk/report or by speaking to an operator via the online web chat at www.herts.police.uk/contact
Call the non-emergency telephone number 101 if you have information about where Harry has been.