I live in a small English city in which it is, believe it or not, quite difficult to buy ink. Ubiquitously available, however, is Parker Quink Washable Blue. Is there any reason why I shouldn't use this in a range of vintage and modern pens, please?

I would think that it is fine. I don't own Parker Blue, but I have Parker Black, and I use it in my P51 with no problems. Parker Washable blue seems to be regarded to around the forum as a trouble-free ink. I personally just don't like the color and the fading that takes place with it, but I have used it, and it is well behaved.

The only bottled ink that I've ever seen in a "normal" (non pen specialized) store is Cross, which The Paper Store carries. Most office supply stores carry Sheaffer, Parker, and Mont Blanc cartridges. Because I don't use carts, I buy my ink online, or at a pen shop which I rarely go to because it is far away from me. If you want more variety, I would check out Fountain Pen Hospital, Pendemonium, Swisher Pens, or some other site of that sort.

Don't worry, there's nothing to be embarrased about! This is what the forums are for!

It is a lovely, lighter blue that doesn't seem to fade in the way that Quink Blue-Black can fade.

There are, as far as I know, no chemical or physical reasons for not using it in any pen.

The only problem you might have is that the Quink inks are not as free-flowing as some others like the Private Reserve range. That means if a pen is a 'dry' writer, the Quink can really bring out that property in the pen.

As well, it is washable. Depending on context (shirt cuffs vs envelopes) it can be a good or bad thing.

....then you must be talking about Canterbury!! If not, then the lack of available ink (other than Blue or Black) must be endemic to all small cities in England. Groan!

try thewritingdesk.co.uk (I'm a happy customer)

I use them all the time, for my inks and paper, and am also a happy customer!! They are so quick. It would just be nice to be able to go into a REAL shop and talk to someone occasionally.

Parker Washable Blue Quink will not hold up if a document becomes wet. In addition, I have noticed that it has a habit of fading, even when not exposed to sunlight.