This school photo postcard was recently offered for sale on eBay, and shows (according to the slate), St Mary's RC school, or a class from it.
The card was postmarked as being sent from Birmingham on November 23rd 1910 to Miss A Hales in Mountain Ash, Glamorgan. 
Currently, and as far as I can gather, there's only one St Mary's RC Primary in the Birmingham area, and that's on Vivian Road in Harborne, and it certainly would have been around in 1910.
One of the students is marked with an 'x' and I would assume it's a relation of the senders, who are signed as 'L + H'. I tracked down the postcard recipient in the 1911 census - it's an Agnes Hales, who was the head teacher of the school in Mountain Ash.
Her oldest sister was Lillian Hephzibah Hales, so it could be a relation of hers,  although I couldn't find any evidence of her having married an 'H' - and there aren't many Lillian Hephzibahs to choose from. 
There's not much distinctive in the photo (apart from the brickwork around the window and the wall itself) to say it is or isn't St Mary's Harborne. Perhaps you can help identify it? 
The Hales family themselves are from the Erdington area, and there don't appear to be any St Mary's RC schools in that locality.
updated by @iamtimbo: 17 Aug 2015 10:08:30