Nest Egg?

This afternoon I hung the window shade for the first time this year to keep out the sun’s heat and two swallows flew into the newly darkened interior. They sat on a shelf under the window for a few moments and then calmly and expertly flew out of the door (with none of the panic and clattering about of a starling or a pigeon for example).

According to the RSPB website, swallows prefer outbuildings which provide dark nooks and crannies for nesting, as these are cosy in cold weather and cool when it is hot and they must have sensed the Egg was worth a quick reconnaissance. As they can enter a building through a very small hole, my open hatch was not going to provide any difficulty.
Earlier in the week two deer approached the Egg door only for me to startle them and drive them away. I think the deer will show up on my time lapse cameras, but the swallows were too swift (and I was to mesmerised) to give any time to pick up a camera.