Lincoln's Inn is one of the four Inns of Court. These Inns are both professional bodies to which all barristers in England in Wales belong, and physical places which host dining, training, governance, and also many barristers' chambers. While those chambers are now offices, historically many lawyers also lived here. The combination of functions meant that space was required, and in the 1680s Lincoln's Inn was extended by the building of New Square at its border.
The process of expansion and development brought its own disputes and agreements between Henry Serle, who claimed and built upon the area of empty ground which is now New Square, and his neighbour the Inn. A rather charming plaque is evidence of one of them. 'T - IG' stands for 'Treasurer - John Greene', and 1693 is the date it was placed here. Most interesting is the text: 'This wall is built upon the ground of Lincolnes Inne no windokes [windows] are To be brocken out without Leave'. It refers not to smashing windows, but to adding them to the wall.
Other plaques can be seen around the Inn which follow this format of a letter 'T', the Treasurer's initials, and the date of building work. A particularly good selection appears on the facade of Wildy's legal bookshop.