The papers are available on Findmypast or
https://www.britishnewspaperarchive.co.ukI don't have a subscription to the latter, but you can do the search which will show the start of the text.
Use the 'advanced search' and enter '6 Doctors Buildings' in the 'exact phrase' section
On the 1939 register, there are two properties in Cumberland Place.
No. 1 is the Thomas family and the first line of no. 2 is blank, but there are two blanked out spaces following it. I wonder if that is where the children might have been, although not usually blanked out at their ages.
Cumberland Place post code is LL42 1ES and, if you use the satellite view on Bing Maps, you can see the numbers 1 and 2.
David