And thus we get a little floor plan of the left-turning entry room.

• 01.002 The best rooms were all on the left-hand side (going in),

It is a two-word word in its OED entry, hyphenated in the examples.

“latecomer, n.” OED Online, Oxford University Press, June 2017, http://www.oed.com/view/Entry/390883. Accessed 15 September 2017.