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So, the letter is addressed to Miss. E. M Blackburn-Brown, in Preston. A quick search of ancestory.com and there's one in the right area, but I'm not paying to join up just yet. I'm going to really look at the photos and see if one person turns up more than the others.I've been looking and so far, there's one lady who shows up more than others. Most of them are from 1920, the year of the letter, but a couple are later. One of the pictures, with the lady playing tennis is labelled "Miss Blackburn-Brown". 

Is this the lady who received  the letter from her friend in June 1920? 

Also, in the box are some tiny pictures, in a tiny envelope addressed to Rev Blackburn-Brown, S James Vcg, Darwen.  

A quick google search of Reverend Blackburn Brown, Darwen, brings up a lot of results. It looks like he was a firey man, calling people to do their duty in a time of war.  One rousing quote form him is detailed in this website. 

"The cowardly, the selfish, the idle and the self-indulgent are not doing their duty at this critical time ... We say deliberately that it is a sin and a shame for any man who stops at home for any reason, however good, to do simply nothing for his country."

I have had a quick look at the house on google maps - I'll be looking out for something similar in these pictures. Not sure it's going to be that easy though, as this place looks really new. 

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