LONDON, Aug 1 (Reuters) - U.S. firms Blackstone (BX.N) and Hudson Pacific Properties (HPP.N) said they planned to create a major film, TV and digital production complex in Broxbourne, north of London, in the first overseas expansion of their Sunset Studios platform. Funds managed by the two companies had acquired a 91-acre site, 17 miles from central London, for 120 million pounds, they said on Sunday, adding that the total investment would be more than 700 million pounds ($975 million). Subject to planning permission, they said they would build a world-class film and television studio campus, creating more than 4,500 permanent jobs. Investment firm Blackstone last year bought a 49% stake in real estate company Hudson Pacific"s Hollywood media portfolio, comprising 35 sound stages and offices, including the facilities where hits "La La Land" and "When Harry Met Sally" were made. Blackstone"s head of real estate Europe James Seppala said the partners intended to deliver a studio facility that would help ensure that Britain continued to be a premier destination for production. ($1 = 0.7191 pounds)