I have two postcards sent to Muriel Mackenzie, "St Audries", Blossomfields Road, Solihull, Birmingham, both mailed from Eastbourne, Sussex:
1) Postmarked 19 Jul 1914, signed Elfrida Evans.
2) Postmarked 3 Aug 1914, signed Harold.
I can't remember where I got these - sorry! Might have been Ebay or might have been in person.
Neither have any connection to me, so send me a PM if you would like them, and will happily send on to someone connected to Muriel.