I attach photos of an opaque turquoise blue example and the trademark and lozenge from an opaque white example. I know both the white and blue examples were marked on the flat part of the underside but can't recall if there was a second set of marks.
No offence, but steering back to the subject matter in question, I was able to retrieve an example of one of the plates you have mentioned during my searches, but there is no mention of another marking. On the 6th picture, which only shows 2/3rds of the plate, where I was hoping a marking would be visible in the same area as mine.
Ebay Item No. 151039240214
good piece Otis - nice find.
Some moulds were in service for some considerable time, which is one of the reasons for the occasional poor legibility of lozenges and Rd. Nos. - another reason will be as Fred has pointed out that it was simply a poor pressing.
Sometimes it's possible to find pressed glass with Reg. details so poor that it makes you wonder for how many years they might have been used.
If you would like me to have a look at the original Registration details in the U.K. archives, let me know. 
Thanks Paul, I must say, the lozenge and Rd No.s emboss marks are prominently raised and clearly visible to the eye. The photos I've taken, don't really do justice. This would indicate to me that the mould might be an earlier piece from the original cast? Please, don't quote me on this, I am only summersizing from past items posted, where markings have been poor and comments have been made. You mentioned that Fred had pointed out about poor press marks:
I presume that the 'd' in 'Rd' sometimes appears to be missing because of a worn or badly cut mould, and sometimes because of insufficient pressure during the actual pressing process. It's the letters and digits in the internal angles of the lozenge that are the important date indicators (the Roman numerals in the circle at the top indicating the registration Class - in this case III for glass).
This gave me reason to look at the marking on my plate again. During my observation I have noticed that the 'R' is central within the located area and there would be no room to for the 'd'. So I would not describe my plaque as a defect in the mould or characters/numbers missing, hence, my reason for querying that there is only a 'R' and not 'Rd' in my previous reply.

It would be a pleasure if you are able to devote your time to look up the original reg. details in the U.K. So, in answer to your question. Yes please!
