MASKED robbers put two men in their 60s through a terrifying ordeal during a raid on a house in Halifax.
Michael Nelson, 34, was one of three balaclava-clad raiders who forced their way into the Northowram home of Alan Mackereth before attacking him and his friend last November.
The retired optician needed nine stitches to his head afterwards and his accountant friend Duncan Turner suffered a broken jaw.
Prosecutor Michael Greenhalgh told Bradford Crown Court Mr Mackereth was kicked and punched before having a chair broken over him.
Mr Mackereth described blood running down his face and the court heard his attackers demanded car keys from him.
Mr Mackereth handed over the keys to a Vauxhall Corsa and the keys to an Audi TT were also snatched, but the intruders eventually fled without the vehicles.
One of the robbers is alleged to have been carrying a knife, but the weapon was not used.
Police linked Nelson, of Greenholme Court in Holme Wood, Bradford, to the robbery after Mr Mackereth’s blood was found on his shoes. He admitted robbery.
A judge sentenced him to an indefinite jail term for public protection after concluding he posed a significant risk of serious harm to others.
Recorder Duncan Smith described the incident as a “mob-handed attack” on two people “not in the first flush of youth”.
He said: “It involved the intrusion into someone’s home. The occupants, and you’ve seen the photographs, show elderly people.
“They would have been startled by your invasion and therefore they were vulnerable people.
“Violence was meted out indiscriminately to both. A weapon was used. A chair was broken over one of them.”
His barrister Stephen Wood said Nelson had not been in serious trouble since being released from a five-year term in 2006 and now had a partner who supported him.
Nelson, whose previous convictions include robbery and wounding, must serve at least 40 months behind bars before he can apply for parole.
He will only be released if the parole board is satisfied he no longer poses a risk.