A medieval church which is known as the “cathedral of the Broads” has been awarded a grant of more than £150,000 which will ensure a leaking roof can be repaired and thereby help preserve a historic rood screen.

St Helen’s Church, in Ranworth, has received a total of £155,000 from the Heritage Lottery Fund which will help to pay for repairs to the roof of the medieval church, without which the painted wooden screen could be damaged.

The rood screen, one of the finest in England, dates from the early 1400s and shows a series of paintings of apostles, saints and martyrs. It was defaced during the Reformation in the 1500s when religious imagery was destroyed.

St Helen’s also has a rare illuminated 15th-century Antiphoner, or service book, and a medieval Cantor’s Desk.

The Rev Nick Garrard, rector of Ranworth, said: “We are delighted that our medieval treasures will be protected and preserved for the future with the help of the Heritage Lottery Fund. Having survived the damage of the Reformation and centuries of neglect before being lovingly restored, it would have been tragic for the rood screen to have been damaged by a leaking roof.”

Work will soon begin to monitor the microclimate inside the church to see how much moisture has already begun to affect the screen. But the main bulk of the work will be the renewal of the lead roof and upgrading of gutters and drains. Robyn Llewellyn, head of Heritage Lottery Fund East of England, said: “We are delighted to support Ranworth PCC with this award of a first-round pass enabling them to develop their application further.

“This is a really exciting opportunity that will make the building watertight, as well as providing interpretation to broaden understanding of the painted rood screen for the thousands of visitors the church receives each year.”

St Helen’s Church, which overlooks the River Bure, is a popular destination with tourists and educational groups, attracting about 50,000 visitors a year.

But despite money from the HLF’s grants for places of worship, the organisers of the church’s rood screen appeal still have to raise around £25,000 to meet the full cost of the work.

The church will be hosting a Christmas tree festival until Sunday with nine large trees decorated by local groups, including 1st South Walsham Guides. For details call 01603 270769.