A great many QOOH men were drafted into other regiments after training; as the war progressed there was no real need for cavalry beyond those already in the field. A photograph in QOOH uniform does not mean that a man did not go on to serve in another regiment. (My Granddad's surviving service record refers to five different regiments). Alternatively he may have been discharged for medical reasons before he could be sent to France, which would support your family's thought that he did not serve overseas. The previously mentioned (other) Benjamin Ravenscroft did serve overseas, arriving in a theatre of war after the end of 1915.