A Sikh gang was found guilty by a British court on Wednesday of slashing the throat of the Indian general who oversaw the 1984 assault on Amritsar Golden Temple.

Two men and a woman were convicted of attacking retired lieutenant general Kuldip Singh Brar, 78, as he walked through London's West End entertainment district with his wife Meena on September 30 last year.

Another man has pleaded guilty to the attack.

The court heard the gang targeted Brar in revenge for his leading role in the attack -- Operation Blue Star -- against Sikh militants in Amritsar, northwest India, which left at least 500 people dead.

The raid was aimed at flushing out militants who had occupied the temple, which is considered Sikhdom's holiest shrine. The militants were demanding an independent Sikh homeland.

Brar survived the knife attack, which left him with a 30-centimetre (12-inch) cut across his jaw and neck and a separate eight-centimetre (three-inch) cut to the jaw.

Mandeep Singh Sandhu, 34, from Birmingham in central England, and Dilbag Singh, 37, and one woman, Harjit Kaur, 39, both from London, were all convicted of wounding with intent by a jury after just an hour's deliberation.

Southwark Crown Court in London heard that Barjinder Singh Sangha, 33, from Wolverhampton near Birmingham, has already admitted the charge.

The defendants showed no emotion when they were convicted. The trio, along with Singh Sangha, will be sentenced on September 19.

The prosecution said the victim's role in the Indian Army, overseeing "a number of military operations... made him a target for Sikh extremist groups" and argued the defendants had mounted "a highly premeditated assault".

Kaur was described as playing a crucial role in the ambush.

She boarded the same bus as Brar and his wife of 28 years to track their movements and phoned through reports to the attackers who lay in wait.

Brar and his wife, who have visited London every year for 15 years, had headed from their hotel to the West End when the attack took place.

The prosecution said Sangha "drew a knife as the other men held the victim".

The victim has survived several assassination attempts and still receives death threats.

Brar, giving evidence by videolink from India, said as a result of the attack his protection ranking was raised to the highest possible level in India.

Mari Reid of the Crown Prosecution Service's Counter Terrorism Division, said: "The couple were set upon in what was a swift, effective and terrifying ambush; Sandhu and Singh held Lieutenant General Brar down as Sangha slashed at his neck with a knife.

"The group clearly targeted Lieutenant General Brar in revenge for his actions during his military career and today's convictions are another reminder that the UK will not tolerate extremism of any kind."