Attention: Question about black-out at night time

[Les]

A quick search revealed this web-page -

http://www.homesweethomefront.co.uk/...lackout_pg.htm

Which states -

"...Businesses faced even greater difficulties with the introduction of the Blackout. Many factories had glass roofs which had to be painted black meaning that workers had to work day and night under the glare of artificial lights..."

So, it looks like the windows were painted black for a few years.

Hope that helps.