Painting by numbers on a record-breaking scale at the Old Royal Naval College did more than reveal Will Palin’s struggle to stay between the lines.

The director of conservation at the World Heritage Site said the project in the Painted Hall – which spanned a 2.5m canvas with more than 7,500 shapes – was a fun way to raise awareness of Sir James Thornhill’s intricate ceiling.

The images housed inside Sir Christopher Wren’s landmark Greenwich building have been hailed as “the UK’s Sistine ceiling.”

They were recreated with an array of colours corresponding to numbered outlines in the three-day project to mark Thornhill’s 340th anniversary – now Europe’s biggest painting-by-numbers.

Will said: “We didn’t quite know how the public were going to get stuck into it.

“But from the moment we set up in the covered tent outside the visitors centre it captured their imagination.

“Kids were coming in and painting and, much to the frustration of their parents, they carried on painting when their parents wanted to go off.

“It was a nice way of engaging people with the work of art.

“I did number four – and it was a grey colour. I’m not very neat and tidy – some of the children put me to shame – so I felt I had to retreat before I became too embarrassed.”

The Old Royal Naval College, Greenwich

The last brush stroke of the three-day project was applied on Saturday (July 25).

As well as marking the painter’s anniversary, the recreation allowed the public to engage with the specific images on the canvas, which took 19 years to complete.

The colouring-in also kicked off the next phase of the ORNC’s conservation work to preserve and clean the ceiling of the lower hall, starting next summer.

It will take just over two years to complete but visitors will be able to get up close and personal with progress by mounting scaffolding installed to watch the experts at work.

The stone space underneath the college will also be converted to house a cafe.

“There are some very big changes – and a lot to look forward to,” said Will.