The Ecclesall Ale Club opened their doors to great acclaim on Ecclessal Road back in November and have enjoyed a successful few months.
The bar is owned by the Brew Foundation Brewery, a father and son team of James Eardley and his dad Robert.
However, a disappointed James took to Facebook on Saturday afternoon after a treasured family heirloom was stolen from the bar.
James posted on their Facebook page that a decorative glass tankard was stolen from a display cabinet.
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He said that the tankard belonged to his granddad and was, in turn, given to him by his dad.
James has shared an emotional appeal for the customer to return the tankard and said he would have 'no hard feelings' if the item was returned.
He posted: "Sad to have to ask this but can the customer who stole the decorative glass tankard with the metal bell on the lid please return it? It belonged to my granddad and was in turn given to me by my dad.
"It means a lot to me and I thought it would be safe in the display cabinet. We put these things in the pub so it's a nice environment for people to drink in, not for people to take home.
"We all do silly things when drunk so there will be no hard feelings if you bring it back, or contact me, or simply secretly leave it in the pub next time you're in.
"I'd respect you for doing so and it would mean a lot to me."