It looks very much like this is a stupid bug in the server that supplies the data stream I was retrieving. s/\r\n//g'ing out the carriage return and linefeed characters has corrected the fault.

I am saddened that I did not think of this, but saddened further that a service purported to be an OS neutral stream is, in fact, anything but.

As usual, the wise here pointed me in the direction of solution, and sacremental wine is available in the bar.

*** EDIT ***

The square brackets went, but you know what I mean!