The public body charged with looking after England’s historic environment has called for proposals to overhaul a “concealed” Georgian church linked with the rise of non-conformist movement to be reconsidered.

Plans submitted to Hambleton District Council by the elders of Zion United Reformed Church, which is accessed behind an arch off Northallerton High Street, seek consent to redevelop the site featuring two grade II listed buildings into “an integrated site that is fit for 21st Century worship and community activities”.

The proposal includes repair work, accessibility improvements and energy efficiency work to the chapel and hall.

The scheme follows a survey of the 1819 chapel and 1852 former Sunday School hall which found while both buildings were in good condition for their age, there was an urgent need to address a backlog of maintenance issues, caused by water seeping in through the roof and bricks.

Another significant issue is the repair of the brick garden wall and buttresses, which surveyors found to be in “a very poor state”, and would present a safety risk if not repaired soon.

A church meeting in October saw unanimous support to commit up to £70,000 from available church funds to a development programme, to sell the minister’s house to fund the programme and to seek grant funding from a range of bodies, including at least £200,000 from the Northern Synod.

The meeting was told although the development of the site would go in tandem with plans for developing its mission, improved facilities in a church could encourage people previously unconnected with the church to use the building.

The application states in remodelling and refurbishing the buildings the elders want to provide an “environment that is hospitable for non-worship users as well as their congregation, and a facility that is suitable and attractive for community use”.

However, Historic England has concluded the proposed works would harm the buildings' heritage as well as the surrounding conservation area.

The body said it had found the exterior architectural form and character of the grade II chapel and its relationship with the associated hall make an important contribution to its heritage significance, and that of Northallerton conservation area.

Underlining the buildings’ importance, they said the architectural character and position of the buildings in Northallerton were important in understanding the development of non-conformist activities in the early to mid-19th Century.

A Historic England spokesman said: “The move to a central High Street location and use of classical detailing to the show-front revealed the burgeoning confidence of the then congregation. However, the relative seclusion afforded by the hidden entrance, and the articulation of both buildings in a very unconfrontational manner, demonstrated a prevailing cautious attitude to worship.”

Historic England said the proposals such as the introduction of a new side entrance would cause a modest level of harm to the grade II chapel and national planning policy required for there to be a public benefit which outweighs the harm.

The body stated: “We do not consider that there is any justification for the level of harm arising from the proposed new side entrance in its current form…

“We remain supportive of the applicant’s commitment to these buildings and their long-term future. Alternative approaches which avoid elaborate architectural detailing or projection are possible.”