All: the number of good suggestions is really overwhelming! In addition to the contributions in this thread I got a message with a very promising hint on an article on
http://newspapers.bl.uk/blcs/ , obviously mentioning Gertrude L Robins in connection with a college and an address in Church End (!). Thank you all for your help!
So, there is some homework to do now... of course, any further suggestions are still very welcome!
@ Spidermonkey: the will... no I did not buy it yet. I was assuming only Mr. Dawson would be mentioned after I found the probate calendar entry "Dawson Gertrude Louise of 46 Berner's-street Middlesex (wife of Charles Edwin Dawson) died 24 December 1917 at Shotter Mill Surrey Probate London 28 March to Charles Edwin Dawson lieutenant H.M. Army. Effects £ 50." But you are right, this is something we can chase! Especially since "my" Gertrude's elderly sister Elizabeth Caroline died in 1958 only.
@BarbaraH: As arevans777 said, "looks like an excellent resource"!
@avm228: No, no photo's of Gertrude the schoolmistress, no photos of her parents either. A pity! Your remark re. the census, was it taken on a specific day countrywide? I was not aware of that...
@spidermonkey (once more), re: the Robins siblings : have to review how much we have about the siblings... for sure not all details. But same first names + birth year of a second Gertrude L. in the same family... hm... and still, the main reason for our doubts is that "Irish father" thing (one possibility for that could of course be that the guy being her father on paper was not her father in reality and she knew that... IF we are talking about ONE Gertrude).
If anybody has the free access to the British Newspapers mentioned initially, it would be great if you could look up
Publication Date: on 30 June 1900
Search: Robins n3 Station
for us. I just asked my co-researchers and am waiting for their reply now. Otherwise I'll go ahead and buy the 24 hours access tomorrow...
All the best,
Gudrun