Almond Valley Heritage Centre, in Livingston, branded the social media clip "completely irresponsible".

Buckfast is an alcoholic drink consisting of fortified wine and caffeine.

After the footage was sent to the centre on Monday evening, a spokesperson posted on Facebook: "This is not ok. We have received an influx of messages tonight of someone (whose name we have removed) giving Buckfast to one of our horses to drink.

"Completely irresponsible, this could cause serious issues to our gentle giants."

The incident occurred on a public footpath near the horse paddocks while the family-friendly museum was closed.

The centre spokesperson added: "We do not allow people to feed our horses, or let them drink Buckfast for a reason, that reason being it could make them terribly ill."

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The Scottish SPCA said it has not received any reports of the incident.

Dr Robin Chesters, director of Almond Valley Heritage Trust, later told Sky News that no harm came to the horse and accepted it was a "silly thoughtless moment" that those involved in "regret".

Dr Chesters added: "In this instance, no harm seems to have been caused, but the consequences could have been far more serious for our big, gentle and trusting Clydesdale horses."