A mother has made an impassioned plea to get back the red hat her daughter was wearing when she passed away, after it was stolen last week.

Katie McGregor's baby Isobel passed away on 26 January 2013 after she was born prematurely and she has kept the tiny red crochet ever since.

It's believed that the item went missing on April 2, at 9.30pm when her leather satchel, which contained the hat, as well as many other valuable items, was stolen. It was taken when Katie was at the Carpenter's Arms pub on Whitfield Street in London.

She said: "Nothing else matters – the laptop, phones, everything else they can have, just please, please give me my angel’s hat back."

"It’s everything to me, it’s a link to my daughter and it reminds me of her. I can’t bear to think I won’t have her hat back, I can’t explain how much it means to me."

So far the police have been unsuccessful in finding the hat but many have passed around the message on social media.

Thousands of people have already tweeted the message #findisobelhat on Twitter and over 1,300 people have joined the Facebook group.

The suspected thief is believed to have made his way towards either Goodge Street Station or Warren Street and has been described as a male of average height with long greasy black hair and glasses.

Anyone with information is encouraged to contact the police on 101, quoting the incident number 10725/02APR14, or to email findisobelhat@gmail.com.

Mother makes heartfelt appeal on Facebook to get late baby daughter's hat returned