Paul presented the following explanation :

2) "If it continues, see a neurologist" said the other.
I award points for that answer.

I had a consultation, + an MRI where they discovered I'd had a minor
stroke long ago, plus a narrowed artery to one side of my face, so they
wanted my BP to not fall too low.

If you're a "strict stay at home, no risks for me thanks"
person, just order a BP machine and have it delivered.
The little battery machines are relatively cheap.
I could afford one. I check BP twice a day and log
it. The drug store had three prices for them.

All good advice and monitors are not expensive in the great scheme of
things. I bought one from Argos, which uses bluetooth to send its
recorded BP to my Iphone. That makes it easy to forward them on to the
medics if they ask for them, which they do quite regularly.

I don't make a point of checking it regularly, rather I check it if I
have concerns, or a change in meds, or during the week before an
appointment - because they always ask for it.

I don't do the measurement at a regular time of day, rather I take
several BP checks at random times, with a note of what I was doing at
the time. That a result of trying to collate why I was going dizzy and
my BP falling under certain circumstances.