UK George V Sg#385A No Watermark¿?

I would like to show you this copy of George V that I have identified as SG#385a from 1920. The fact is that normally for a first classification of these models, I separate them by their watermark and then by their color...but in this stamp even now it is not I can see the watermark, but by comparison with the SG#426 models that I have I could see that the color would correspond to a reddish purple, and measuring the perforations, something that I never usually do in these UK models, surprise 14 perforations in all sides with what for me this stamp could be SG#385a.
What I can't see is the watermark in any way, I don't think it has one...maybe an expert eye can identify something...

Agree with you ,got a nice stamp . Yes as a perf 15X14 in rose lilac. it would be the early issue of 1912-13 Scott 167b .

@Murasama, you identified the stamp correctly.

On the left of the picture, you can see what looks like the bottom of the "E" from the marginal postage watermark that appeared in the righthand sheet margin. The watermark is offset to the left (right as seen from the back). It is the 'Simple Cipher' watermark that appears on the right half (left as seen from the back) of the stamp. Your stamp is from column 12 of the sheet.

Thank you, your approval fills me with pride, I finally classify a good stamp well hahahaha