A man died just hours after he was brutally beaten and threatened with being set alight by his neighbour, who was angry with him for having voted for Brexit, a court has heard.

Duncan Keating, 58, was hit with a parasol, repeatedly punched, doused with fertiliser and threatened with being burned alive during an attack by neighbour Graham Dunn, 62, in the communal gardens of the retirement apartment complex in Manchester where both men lived.

Keating was found dead in his apartment six hours later, kneeling by his bed.

Keating had been planting seedlings when he struck up a conversation with Dunn, asking him how he had voted in the referendum a few days previously.

Both men had been drinking that day, and when Dunn found out that Mr Keating had voted to leave he flew into a rage, the Manchester Evening News has reported.

Prosecutor Maria Brannan told court: “The defendant became aggressive, asking if he had children, saying ‘fucking think about their generation, not yours’.”

He added: “I’m going to have you, let’s fucking sort this out.”

CCTV footage showed Dunn launching a 15-minute-long sustained attack against Keating, repeatedly pushing and thumping him despite being met with no resistance. At one point Keating fell heavily against a stone ornament in the centre of the garden after being pushed a distance of a few feet.

One witness described seeing Dunn douse Keating with fertiliser while shouting “I’m going to burn you.”

Police attended the scene but left after the men told them there was no problem.

In the hours after the attack Keating was seen with a tennis ball sized swelling to the left side of his jaw and with a swelling on his arm, but dismissed it as “handbags”.

Dunn was seen going to Keating’s flat three times in the hours between the attack and Keating’s death at 7.25pm; he later complained that the victim had broken his nose.

The coroner found that Keating had been drinking and taking drugs on the day of his death, ruling that his death was caused by positional asphyxia and intoxication through consumption of alcohol, methadone and cannabis.

Hearing the case at Manchester Crown Court, Judge Martin Rudland said of Keating’s death: “Grave consideration has been given between this event, and that tragic death, and the consultant pathologist has concluded his death was due to matters unrelated to the assault.”

Dunn admitted assault occasioning actual bodily harm against Keating, for which he was sentenced to four years and five months’ jail time.

Sending him down, the judge told Dunn: “We see from the glaring CCTV footage of the event that you picked on him and you bullied him and you wouldn’t let up.

“You began by using a parasol, then we watch you punch him while he’s lying backwards in a wooden chair in the garden, and you then pursue him round the garden, shouting at him, berating him.

“He is doing nothing but backing away from you at all times, but you goad him, you harass him, you follow him, you try and out-step him and out-manoeuvre him, and when you get close to him you punch him, not once, not twice but three times.

“It was an unpleasant, brazen, bullying event. There is no way you would have behaved as you did to someone who was of your size and strength, and that’s quite apparent from the way in which you teased and goaded him.”