Is it proper to use a colon followed immediately by a hyphen?

Question

I have seen some writing where people have a list or a figure in writing and they will write something like this:

The information is provided in Image 3:-

Is that correct? Is this a British style?

Answer 1

According to Nick Marten's The Secret History of Typography in the Oxford English Dictionary, a colon followed by a dash is a typographical mark that the OED refers to as the dog's bollocks:

Citing usage from 1949, the OED calls this mark the dog’s bollocks, which it defines as, “typogr. a colon followed by a dash, regarded as forming a shape resembling the male sexual organs.” This is why I love scrounging around the linguistic scrap heap that is the OED. I always come across a little gold. And by “gold,” I mean, “vulgar, 60-year-old emoticons.”

Marten does not further elaborate on its purported usage, but others do:

In Britain the exclamation mark is sometimes referred to as a dog’s prick, and that, further, the combination of a colon and a dash (:—), out of fashion now but long used to represent a restful pause, is known as a dog’s bollocks.

Modern style guides seem intent on banishing its usage to history. For example, the University of Sussex has a strong opinion on the matter:

The colon [is] never preceded by a white space; it is always followed by a single white space in normal use, and it is never, never, never followed by a hyphen or a dash — in spite of what you might have been taught in school.

I'd love to find some examples in print, but as you can imagine:— it's extraordinarily difficult to google.

Answer 2

It's correct, because it is a recognised, well-known usage. However, it is redundant, and in most situations not the best or right usage. I would only use it where there is an established convention for its usage, such as in certain court documents.

Answer 3

This is brilliant guys, thanks - I am a (UK) fiction novel writer and I use this piece of grammar to indicate an attributive that finishes mid-sentence, with the actual quoted speech starting in the NEXT chapter.

Ours is a digital story/publishing concept that requires this odd way of formatting, and no other piece of grammar is really up to the job as regards length of 'pause' and strength of intention as regards separating parts of a sentence that are important enough to warrant crossing chapters, so we brought it back, and liked the idea of recycling old grammar for a modern publishing concept.

Having said that, it is generally considered archaic now, and looks too convoluted within a passage of text, and is, frankly, irritating to try and read past (IMHO) as it visually 'clogs things up' - especially in digital formats.

As well, I have just read a collection (endorsed by Salman Rushdie, no less) that contains wide usage of DASHED commas, DASHED colons and even DASHED fullstops. What grammarians often forget is grammar is ALSO creative.