Potblack,
here is a postcard I found recently showing the Pavilion at Bournville. It is postmarked 30th May 1908. At first glance I thought the writing along the edge was a continuation of the communication, however it is actually a printed caption:
"Don't Forget to send the Bournville Cocoa Coupons, you will be delighted with the prize Box of Chocolates."
Brian