Saint Thomas Becket window in Chartres Cathedral

[2] The window's composition is very different to others at Chartres,[2] in which the main subject's story was told uninterrupted from bottom to top.

These anomalies suggest that the first main circle should be read as an independent narrative and a specific memorial to his visit to Chartres, perhaps even drawing on accounts of him by those who saw him there.

His exile followed Henry II's promulgation on 30 January 1164 of the Constitutions of Clarendon, a collection of juridical procedures controlling the election of new prelates and gave royal courts the right to summon clergy.

The representation suggests an expulsion by force as a criticism of Henry, whereas in reality Thomas willingly chose exile.

The collection of liturgies at Chartres states that Thomas disembarked at Wissant, a village to the south-west of Calais on the Côte d'Opale and that on his journey from there to Sens he met Louis VII of France at Soissons and talked amicably with him.

[2] The images quite faithfully follow the text of the office of matins for the feast of Thomas Becket on 29 December.

The two men's discord arose from the Constitutions of Clarendon, by which Henry attempted to impose his authority on the English church.

To the right Henry is shown higher than the other two figures on his throne, wearing a royal crown and resting his feet on a stool.

[2] The interior's decoration is symbolised by a column and two arcades, supporting a crenellated wall – behind the king is a window (whose opening is shown in red according to convention) through which is seen a covered tower.

Thomas spent two years at Pontigny, ending in 1166, before returning to Sens, where he could spend his exile more safely.

The king's sceptre is over-large and more resembles a herald's mace, underlining his role as bearer of diplomatic messages.

Finally, on 22 July 1170, a patched-up peace was made between Thomas and Henry at Fréteval, allowing the archbishop to return to England.

To the left a crowd welcomes him and presents him with a large processional cross, which recurs in the martyrdom scene.

However, the panel is still ambiguous – a logical reading would be that it shows Thomas' return to England (the wind-filled sail propels the boat towards the left), but the pilot would then be in the front of the boat, whereas he is shown at the back,[4] though that may have been switched to accentuate the panel's symmetry with the image in the fifth register and thus emphasise Thomas returning the way he had come.

[4] However, that coronation occurred on 14 June 1170, long before Thomas' return to England, leading him to excommunicate the Archbishop of York and the Bishops of London and Salisbury who had taken part.

Whichever interpretation is correct, panels 8a and 8b both show the leading English clergy's role in the tensions, with Henry II refusing to receive Thomas but welcoming the excommunicated bishops.

To the left is the red door just passed through by the knights, whilst to the far right is an altar, evoking Christ's sacrifice, although the murder actually occurred in a transept near the stairs up to the choir.

As conventional in images of the murder, Thomas is shown kneeling, with Fitzurse making the final blow into his head and mitre, slicing off the top of his skull and wounding Edward Grim, shown holding the episcopal cross, who later wrote an account of the murder.