Thank you. It looks OK to me too but I have never seen a Dixon's copy up close. Does anyone have a picture of one? There is no doubt the medal has been recently altered. The vendor tells me they did not do the modifications.
I have had a further reply from the vendor as follows
"I have been through our records and see that we purchased the medal from Steve Sewell last year and added the original DoM clasp which came from an erased medal. My records also indicate that the price we sold the medal for was in fact less then the cost of the medal and genuine DoM clasp!
The clasp on the medal is quite genuine and we should have made a note to state that the medal had been corrected, but the paperwork relating to the original purchase and subsequent alteration had been misplaced and **** who catalogued the medal was unaware of the alteration."
This reassures me somewhat as I would have purchased the medal anyway with this information up front. I'm never going to see another Marshall's Horse DOM after all!
I have overcome my temporary panic now! Here is the Morrison clasp with three other single clasp DOMs from my collection. I can't see any variations of note. Now I've extracted them all from the safe I will post full pics and details later.