Spacing is exactly the same as on one of my cars (letter, number, space, three letters) and is totally legal.
I thought postcode AND BS number was required on cars registered after a certain date and plates made after that date too, so they are probably not legal.
There is also a specific font, but that appears to be OK too.

Sound like he was just looking for an excuse to stop you.

I have 2 cars with registrations old enough to not need either BS or postcode, but the plates do anyway.