RM jargon probably, my FIL worked on the railways and was often phoned out of hours about some problem, it was like a foreign language listening to him talking about shunting issues and the like
Yes that makes sense, it i s a Large letter sizen and on Ebay it says being sent 2nd class and no it did not need signing for, i quess it looks like its gone through the senders own franking machine, hence the seller did likely write it on when she packed it, maybe with loads of other packages, makes sense now, thanks.