Sir Ray’s Tindle Newspaper group began buying JP shares earlier this year, in the belief they were undervalued at around 4.5p a share.
He initially purchased 27.9m shares worth around £1.39m, giving him 4.36pc of the company.
The shareholding was later increased to 6.36pc and now stands at 7.17pc, a stake worth approximately £2.28m.
Sir Ray’s most recent share purchase is estimated to have cost in the region of £250,000.
The 84-year-old newspaperman has previously ruled out a full takeover of JP, which has a market capilisation of around £31m.
Johnston Press’s two biggest shareholders are Malaysian billionaire Ananda Krishnan’s PanOcean Management, which owns 20pc, and investment company Orbis Holdings, with 10.7pc.
Sir Ray’s stake makes him comfortably the third largest shareholder.
New chief executive Ashley Highfield has also been allocated 10,471,204 shares in JP under a performance share plan scheme or ‘golden hello.’
Mr Highfield had already purchased 711,818 shares in the company before joining the business on 1 November.