A video of a London underground guard allegedly abusing an elderly passenger has sparked an angry internet campaign calling for the guard's dismissal. The guard, at Holborn station in central London, is heard to say "sling him under a train".

The video, filmed by blogger Jonathan MacDonald, has prompted Twitter users, including the London mayor, Boris Johnson, to express their shock and anger.

"Appalled by the video. Have asked TfL to investigate urgently. Abuse by passengers or staff is never acceptable," Johnson tweeted.

Minutes later a TfL statement was emailed. It said: "We are appalled by the scene captured in this video and will investigate thoroughly and urgently what took place and what led to it. We do not tolerate members of the public being abusive to our staff but neither will we tolerate members of our staff abusing members of the public."

At the time of writing the "TFL" incident is a top-10 trending topic on Twitter, where many have called for Ian's instant sacking. Is this virtual lynch mob fair?

Blogger Terence Eden thinks not.

"I hope that "Ian" doesn't lose his job – I hope that he realises what an arse he has been and learns to treat customers with a bit more respect.

"This video is presented out of context and – although I trust Jonathan's reporting of events – we do only have his word for it. He may very well have chopped off the footage which completely exonerates Ian. Although I can't quite conceive what that would be."

The RMT, the union believed to be representing Ian, has yet to comment.

What do you think?