Cambridge's King's College chapel

Visitors enter King's College chapel backwards in time. Coming through the west doors, they will be overwhelmed by the expanse of fan-vaulting and the dramatic 16th-century windows. From here they enter an area more in accord with the specifications of the college's pious founder, Henry VI, who envisaged a building without too much "besy moldyng". The only figures he wanted carved into its white limestone walls were of Catherine and Margaret, the name saints of his mother and wife, and of the Virgin Mary, to whom, with St Nicholas, he dedicated his chapel. The faces of all three were smashed by William Dowsing's iconoclasts in 1643.

Following Henry's murder in 1471, royal benefactions continued, though sporadically, until Henry VII donated liberally towards the chapel's completion. Building work proceeded westward – as a Tudor monument, full of crowns, roses, portcullises, fleurs-de-lys, dragons, greyhounds, antelopes and coats of arms. It prompted EM Forster to say: "A royal saint might have begun the chapel, but it was Henry VII and Henry VIII who did most of the work; they have the big word, it is their voice that reverberates from the fan-vaulting and pours over the lawn when the west door opens."

Over these political symbols, however, gazes a figure generally unnoticed. On a rose in the south-west corner there is a small half-figure of the Virgin Mary, amid rays of glory – possibly hinting at the transfiguration, but certainly a reminder of the "rose without a thorn", a favourite medieval designation for the Virgin, which resonates through carols such as There Is No Rose of Such Virtue.

Why is this figure there? She could, as one guidebook suggests, be "a fancy of a workman". He would have been a brave man, though, who tampered with a Tudor rose. One can imagine the confusion of the iconoclasts who inflicted such damage upon her sister saints in deciding whether or not to smash a religious image set within a royal one. Or perhaps she was spared because, just like the majority of visitors, they simply didn't notice her.