これまた is a short form of これはまた, meaning 意外な物事や、人の思わない動作やことばに驚いたときに発する語, i.e. interjection used to describe unexpected surprise.
This is my quick translation.
That was a grand work table which was cluttered with all sorts of painting tools that were covering the entire surface; and then, there was also a huge fluorescent light which was positioned in a way that it illuminated the entire surface of the table.
I hope it is good enough.