Theresa May has waded into a row over the decision to drop the word “Easter” from a Cadbury and National Trust “egg hunt”.

The Prime Minister, who suggested she felt the slight particularly keenly because she is a vicar’s daughter, condemned the decision as “absolutely ridiculous”.

But her intervention, which followed one from the Archbishop of York, appeared premature after it emerged that posters for the event were still emblazoned with the word “Easter”.

The row began after the chocolate giant’s seasonal campaign run in conjunction with the Trust was called the “Cadbury's Great British Egg Hunt” – some 300 egg hunts will take place this year at National Trust properties.

Ms May told ITV News: “I'm not just a vicar's daughter – I'm a member of the National Trust as well.

“I think the stance they have taken is absolutely ridiculous. I don't know what they are thinking about frankly.

“Easter's very important. It's important to me. It's a very important festival for the Christian faith for millions across the world. So I think what the National Trust is doing is frankly just ridiculous.”

The Church of England sparked the row, with Archbishop of York Dr John Sentamu accusing Cadbury of “spitting on the grave” of its religious founder, Quaker John Cadbury, by removing references to Christianity's most sacred festival from the spring event.

Dr Sentamu told the Daily Telegraph: “If people visited Birmingham today in the Cadbury World they will discover how Cadbury's Christian faith influenced his industrial output. He built houses for all his workers, he built a church, he made provision for schools.

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"It is obvious that for him Jesus and justice were two sides of the one coin.”

But the National Trust said that suggestions it was downplaying the significance of Easter were "nonsense" while the chocolatier dismissed the archbishop's claim as “simply not true”.

A spokesman said: “We host a huge programme of events, activities and walks to bring families together to celebrate this very special time of year.

“A casual glance at our website will see dozens of references to Easter throughout.

“Our Easter events include our partnership with Cadbury, which has been running Easter Egg Hunts with us for 10 years. They’ve proved consistently popular with our members and visitors. As part of its wider marketing activity at Easter, Cadbury will always lead on the branding and wording for its campaigns.”

A spokesperson for Cadbury said it is “simply not true” to claim that Easter does not feature in the company's marketing communications.

“It is clear to see that within our communications we visibly state the word Easter. It is included a number of times across promotional materials ... Our Easter partnership with the National Trust is also synonymous with Easter, and we make it clear throughout materials that it is an egg hunt, for families, at Easter.”