Paul Delaroche’s The Execution of Lady Jane Grey, 1833, has become one of the nation’s best-loved paintings. So says the National Gallery where the enormous canvas has been on view since its rediscovery in 1973 and first exhibition at the gallery two years later.

They base this, they tell me, on the numbers of postcards sold and by the foot traffic; more work has to go into re-polishing the floor directly in front of the picture apparently than anywhere else in the gallery. It certainly created a sensation when it was first shown in the Paris Salon in 1834, so much so that it needed a crush barrier to protect it, the first picture to gain that honour.

Now, 35 years after it came back on view, the National Gallery honours Delaroche’s masterpiece by giving it centre place in a major exhibition that places it in context with his career as a history painter, and other artists who worked in this then fashionable genre.

The French artist Delaroche (1797–1856), who first visited England and Scotland in 1822, had a penchant for poignant scenes of history, particularly British, and particularly those with themes of martyrdom and usurpation. These were the works that made Delaroche’s reputation, yet his name became forgotten during the course of the 20th century.

It is a melodramatic canvas: set in the Tower of London, the blindfolded white-robed maiden reaches forward, sweet white hands groping her way to the executioner’s block under the gentle guidance of the lieutenant of the Tower; meanwhile maidservants swoon, turn their backs on the unbearable, and the executioner waits.

It is also somewhat static. It has a kind of preset, posed, tableau-esque quality. But, from what I saw in this show, a sense of drama runs through a lot of Delaroche’s work. He had a considerable interest in the theatre, the tableaux that became fashionable at the time, and used his ingénue actress friend Mademoiselle Anaïs as the model for Jane (a newly discovered portrait of Anaïs is in the show).

Delaroche, a talented draughtsman, and some say probably the most influential French painter of the early 19th century, evidently had an eye for detail. See the straw, the textures, the light glancing off her gown.

A lot of myth built up around the nine-day queen, great-grand-daughter of Henry VII, the manipulated victim of ambitious men, successor to Edward VI, deposed a few days later by his half-sister Mary Tudor. Within six months of her death, executed for treason in 1554, her Protestant allies had reinvented her as innocent martyr and victim of Catholic tyranny.

Delaroche had a knack of capturing exactly a moment of pathos. You can see this in many works, for instance Cromwell and Charles I, the victor lifting the lid of the dead king’s simple coffin, gazing contemplatively down at his enemy.

As for why a Frenchman was painting these romantic visions of English history at all, why such fascination existed in France for things English and Scottish, at a time when the country was deeply scarred by the recent French Revolution — I must leave to you, for want of space.

The show, which has an excellent audio guide and is enjoyably instructive, is as monumental an exhibition as its main subjects. It fills six rooms in the Sainsbury Wing with paintings and preparatory drawings, works by Delaroche and contemporaries, and features seven major international loans including The Princes in the Tower, and Young Christian Martyr (both from the Louvre), and Strafford on his way to Execution (private collection).

But I must finish with another great work deserving attention.

Delaroche’s recently recovered Charles I Insulted by Cromwell’s Soldiers, on loan from a private collection, is in room one (by the gallery’s main entrance). Don’t miss seeing it; it’s shown for the first time for almost 70 years. It was a real highlight for me. This masterpiece, made in 1837, clearly references pictures of Christ mocked by his guards.

Having been hung for decades in sumptuous Bridgewater House in St James’s, the London home of the Ellesmere family, the painting was thought destroyed during the Blitz by a German bomb.

Heavily damaged by shrapnel it was rolled up and evacuated to the Scottish Borders where it has remained ever since.

The huge painting is now a third of the way through extensive conservation. Seeing it with its war wounds, more than 200 shrapnel tears, paper patches keeping the painting together, it is unusually moving.

The battered picture of the bearded king, withdrawing within himself, prayer book in hand, taunted by soldiers moments before his execution, had more impact on me than Jane as apotheosis of virginal innocence.

If you are planning to make a day of it, there are two other Lady Jane Grey shows you might like to see — both free.

One is at the National Portrait Gallery (until July 11) and includes a posthumous portrait of Lady Jane, and prints of sentimental history paintings popular in the nineteenth century; the other, at the Wallace collection in Manchester Square, is a display of their paintings by Delaroche — ten oils and two watercolours (until 23 May). The two National Gallery exhibitions are on until May 23.