Toe the line

Or: Gyles Brandreth shame on you!
on the generic complaints program ‘Room 101‘ on the BBC, he claimed that phrase’s origin was from the Houses of Parliament where they have a pair of red lines separating the opposite sides of the room. The problem is that it is a slight confusion. He was mixing up the ‘Thin Red Line‘ phrase and the toeing the line definition. No-one in the houses of parliament would have been bare-footed, so they would have never ‘toed the line‘. The origin of the phrase is most likely military or naval, where people were required to line up at various times for inspection. Convention claims the navy, as most common crewmen on a boat were bare-footed.
The lines in the House of Commons themselves are actually quite thick, and are positioned two sword lengths apart from each other. The principle being that you stayed behind the line during a debate, and thus could not attack your opponent on the opposite side. Such was the animosity of the two sides during certain periods of England’s history that this principle was created, and it is still adhered to.
The origin of ‘Thin Red Line‘ is slightly different. In the mid 19th Century there was an understanding between officers and men that British Infantry would never be asked to stand and face an enemy onslaught in less than three ranks, four was more common. The retreat would be sounded rather than allowing this to happen. At the Battle of Balaclava on October 25th 1864, Colin Campbell’s 93rd Highlanders (Argyll and Sutherland) stood in just 2 ranks and faced a Russian Cavalry charge. It was here that the phrase originated.
There is a similar, but not identical phrase ‘Coming up to Scratch‘, which refers to the scratch line that bare-knuckled boxers were supposed to get to before resuming fighting once they’d been knocked down. If they didn’t come up to scratch, then they were out of the fight.