From what I understand, in the UK it should be used as already stated - personally if there's a holding point designator, I use it (hold AT D1). If there's not, then I may use "hold short of U" - but if I can I'll also give a reason, such as "to allow your marshaller to enter ahead of you". Fortunately, at PH we have plenty of hold points, so the example above is usually the only one used at the entry to the GA apron.
There does seem to be a frequent element of european, and definitely US pilots, who will read back something like "taxi to D1, hold short of runway 24", or "hold short of D1", even when I've given a "hold at", so perhaps it's more commonly used in the US and some parts of Europe?
To me hold at D1 is definite, hold short of runway 24 is, well...how short???