Queen Victoria 1d Red. Plate Numbers?.

At heads rear I can easily make out 7 but what number is next?
What's your opinion, please.

78

Looking at the left side, I see a 1 in the next diamond shape below the 7. so if smauggie's 8 is correct then it is plate 178. n

As far as there being a seven behind the head on the right, I am not sure that I agree. The perforations cut into the design where part of the plate number would be. I see what you are calling a 7, but if you compare that with the 7 on the left, it is clearly not the same.

Wow, thanks for pointing that out, I completely missed that.