AlanM, yes it was an A321, but what the heck.
Impi, not standard phraseology and as an LCE I would be on your case!! Interestingly enough a similar phrase was used in the incident referred to. Such an instruction should never be necessary and is a sign that you are playing it too tight. If the spacing is not sufficient then tell approach - the tower controller is the arbiter of the final approach spacing.
TRUCE for 2003 at Heathrow will concentrate on the problems associated with single runway operations, both in the classroom and the simulator. LCEs will be delivering a presentation covering all aspects of the subject over the next few weeks. Whatever FlapsOne thinks, we will be recommending the "be prepared immediate" phraseology. It adds urgency to the instruction and helps the pilots with situational awareness. Hopefully lessons will be learned and our service levels in single runway operations will improve. And before anyone from a busy single runway airport chips in, prolonged single runway operations at Heathrow is not a common event and neither the pilots nor controllers have enough practice of it to be really proficient. It is a non-standard occurrence and should be treated as such.