OK, to answer the original question. This came about because of a Runway Safety Workshop. It has been shown that reminding pilots of their obligation to read back all the information listed by "radar 707" has a positive educational impact, reduces RTF loading (due to Controllers not having to ask for readbacks when these are not forthcoming), and generally improves safety. At Heathrow this message will be put on the ATIS for one month at a time during January, May and September, and wil be ongoing.