Hi John & welcome to RootsChat.
LancashireBMD is compiled by volunteers from the original registers held at the local register offices. Some (as in your case) have allowed mother's maiden name to be added to the local index before the date at which it was added to national GRO index, which can be quite useful. The transcription looks as though the hand-writing was hard to decipher but plausible from McKeown - which if your ancestor wasn't literate would have been spelled according to how the registrar thought....
From the full GRO index on FreeBMD it seems that the birth is one of those where the registration district was Blackburn which at the time covered these places:
http://www.ukbmd.org.uk/genuki/reg/districts/blackburn.htmlone of which was Oswaldtwistle.
If you want a copy of the certificate you can use the form from LancashireBMD to apply to the local office. You can add a note to the form for other information (eg parents' names) you might then get a copy that is "photocopy style" from the original as some offices can do this.
If you apply to the GRO you'll need to put in something as a check with
their there being more than one birth in that name in the same period.
Modified for spelling - oops
