Grant previously settled a phone hacking claim with the News of the World – also previously owned by NGN – in 2012, donating his substantial damage payout to press reform campaign Hacked Off.
The 62-year-old is now also part of a larger claim brought against the publisher by Prince Harry, giving evidence alongside Elton John and Sadie Fox.
NGN has called for both to be thrown out, arguing they have been brought too late.
Grant, who has previously said that he was shown evidence by police that his phone had been hacked, is a vocal supporter of press regulation.
Grant was a victim of phone hacking, and in 2011 wrote a piece for the New Statesman titled: “The Bugger, Bugged.”
In it, Grant described a chance encounter with former News of the World journalist and photographer Paul McMullan in “remotest Kent” the previous December, which led to another meeting between the pair that Grant secretly recorded.
In the conversation, McMullan confirmed that Grant’s phone had been hacked and alleged that editors at the Daily Mail and News of the World had ordered journalists to engage in illegal phone tapping.
The article was widely publicised, with Grant becoming an unofficial spokesperson for the campaign against Murdoch’s company. He spoke about the subject on Newsnight in July 2011 and gave testimony in the Leveson iniquity that year.
Following the phone hacking scandal, Grant has been heavily involved in the Hacked Off campaign, which campaigns for a “free and accountable press”.
The actor joined its board of directors in 2012 and still posts on Twitter under the username @HackedOffHugh.
In February 2018, the publisher of the Daily Mirror agreed to settle a lawsuit brought against them by Grant. They apologised for taking part in “unlawful information-gathering” on Grant and other celebrities.
Speaking outside the court, Grant said: “This case was not just about what they did to my phone and those close to me… This litigation has made clear that phone hacking and other unlawful information-gathering took place on an industrial scale at the Daily Mirror, Sunday Mirror and Sunday People.”
Once again, he donated the large payout he received to Hacked Off.
In his current lawsuit against NGN, Grant is joined by 7/7 London bombings survivor John Tulloch, the jockey Kieren Fallon, and David Beckham’s father, Ted.