Joe Hillman was an important personality in the late 1880s. His business was mainly in licquour, on and off the premises. There is a book I can't find at present which contains more information, but I attach a caracature of him, published at the same time as Joe Chamberlain got similar satirical treatment. They were both very enterprising people.
So far as the telegraph post is concerned, it seems clear to me that the two diagonal struts were stays to keep the post upright.
Those were the early days of wireless telegraphy, and Joe Hillman being what he was, he would want to be involved. He could well have been contracting to Her Majesty's General Post Office, as they erected their new building on the site of Corbett's hotel soon after.
What also intrigues me about the picture is the tram track (by then disused) which was briefly used for a horse tram service from West Brom to Selly Oak. Business on the Bristol Road was not too good, and the horses found the gradient in Suffolk Street too much for them. So the Bristol Road end was cut off to the bottom of the hill, just past Navigation Street.
Peter