In July last year the Government scrapped £25m earmarked to fund upgrade work at the site including the landscape surrounding the stones and a new visitor centre.
Penrose said: "It is a real step forward in making sure this World Heritage Site is not simply preserved, but also presented in the best possible light for visitors in the future."
"For too long the way it has been presented to visitors has been woefully inadequate – decades of dithering and indecision have got us nowhere. So it’s only right that new thinking and cooperation between parties come together to ensure the whole visitor experience is world-class too.
English Heritage chief executive Simon Thurley said: "These are crucial steps which bring closer the transformation of the currently blighted Stonehenge landscape."
It was hoped final paperwork and funding details would be finished in time to start work in 2012, he added.
Landscape architect Chris Blandford Associates won the contract in 2009 to revamp the site.