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A man has admitted using motor oil and detergent to kill his neighbour's fish and destroy a water pump out of 'sheer frustration and lack of sleep', a court has heard.

Gerry Duffy, 76, of Barnet, north London, was 'driven completely insane' by the sound of a water pump running his neighbour's fishpond.

At Willesden Magistrates' Court this morning, Duffy pleaded guilty on the day of his trial to damaging the pond, fish, water pump and pipes in March.

He had warned his neighbour, Andreas Ptohides, that he would take matters into his own hands if he did not do something about the noise.

Shahid Iftakhar, prosecuting, told the court the 'neighbour dispute' had killed 'five or six' of Mr Ptohides's Koi carp, and potentially caused £585 of damage.

The neighbour claimed £800 worth of damage was caused, Mr Iftakhar said, but today the prosecution stated the damage was £585.

He said: 'The defendant has previously complained to the complainant about noise coming from his garden and has said words to the effect of, "if you don't deal with it, I will" – there was a warning before the incident.'

The prosecution added that Duffy was captured on CCTV having 'climbed into the complainant's garden and damaged the water pipes and pumps'.

In mitigation, Elliott Stern told the court his client had tried to deal with the dispute without resorting to killing the fish.

Gerry Duffy (pictured outside Willesden Magistrates Court today) admitted using motor oil and detergent to kill his neighbour's fish

The 76-year-old told the court he did it out of 'sheer frustration and lack of sleep'

Mr Stern said: 'The man has been driven completely insane by this noise, he's spoken to the complainant several times.

'They initially said they would stop the water pump going but then turned around and said that's not good for the fish.'

An environmental officer came to the house and told Duffy he either had to 'move or close his window', the court heard.

'Out of sheer frustration and lack of sleep, Mr Duffy, out of character, I would say, lost his mind and committed various damages,' said Mr Stern.

Duffy will be sentenced later on Tuesday morning.

This is a breaking news story, more to follow.