My blood pressure is somewhat strange... 140/60 so highish on the 1st one, and low on the second. What does this mean as it has been puzzling me for ages.
Nothing. It's a normal blood pressure, with the first reading around the upper limit of 'normal' (see below). I wouldn't sweat about it. Get it taken again and it'll be different anyway. BP varies a lot and it's the trend which is important, rather than a single reading. Some of these home BP monitors can therefore be useful for that reason. It's certainly a help in managing someone's hypertension to see a series of home readings.
By the by, there are two main causes of a large split (known as the pulse pressure) between the systolic (1st reading) and diastolic (2nd reading). The first is hardening of the arteries which can occur in older people. This gives a very high systolic reading and you may see a BP of the order of 210/80. The other cause is incompetence of the aortic valve. Without going into the physiology of the cardiac cycle, this means that very large volumes of blood are being ejected from the left ventricle, only to cascade rapidly back through the leaky aortic valve. This will give a similar blood pressure, although the pulse has a very particular characteristic and the findings are obvious on listening to the heart and, clearly, on echocardiography.
The debate about what is a 'normal' blood pressure is an interesting one. Basically, there isn't a normal blood pressure. There is a continuum of blood pressure from very low to very high and the higher it is the greater the cardiovascular risk which attaches to it. The thresholds for treatment are coming down all the time, as the data we have get better and better, hence the 'normal' comes down all the time. There must be a limit, however, and I'd be surprised if blood pressures of 135/85 or below will ever be treated.
QDM