Visitors to Madame Tussauds will be dazzled by the Queen's wax figure which features a new crystal-covered dress to mark her becoming the longest-reigning British monarch this week.

The monarch's model has been unveiled wearing a replica of a gown worn by the Queen in 2012 for her official Diamond Jubilee photographs.

On Wednesday the Queen will pass the record set by her great-great-grandmother Queen Victoria who, Buckingham Palace has calculated, reigned for 23,226 days, 16 hours and 23 minutes.

A spokesman for the famous London attraction said: "It's all part of the celebrations marking Madame Tussauds' relationships with Her Majesty the Queen as she becomes the longest-reigning monarch."

He added: "The Queen is the most modelled likeness at Madame Tussauds. It started when she was a little girl when she was modelled on a rocking horse."

Visitors are allowed to touch the Queen's latest wax model, created in 2012, as they pose for selfies, and its popularity means staff are regularly working to keep it looking in the best condition.

The new dress was made to replace an identical one that had been created a number of years ago for the model.

Four workers from Tussauds' in-house team spent 150 hours sewing 53,000 Swarovski crystals on to the intricate white and silver lace gown.

The Queen's waxwork also features a blue Order of the Garter sash and star and on its head is a replica of the diamond George IV state Diadem.

It will be displayed alongside a number of Norman Hartnell and Ian Thomas designed dresses worn by previous wax figures of the Queen, archive correspondence between Buckingham Palace and Madame Tussauds and images taken during the Queen's sittings for the London attraction.