I'm not wishing to extend this discussion too far, but my meaning was that you were suggesting that the phrase "It is recommended that RESAs extend to at least 240m ..... wherever practical and reasonable" (which I know full well comes from CAP 168) has been used to avoid consideration of reducing declared distances.
In a case where the potential seriousness of an overrun is considerable there must be an argument for providing a RESA longer than the absolute minimum. For example, SEN had a RESA on 06 of 90m before the runway extension was carried out. Because there is a railway line beyond the end of that RESA it was decided to increase it to 150m by effectively moving the end of ASDA on 06 an additional 60m to the South-West.
Incidentally, CAP 168 does include the suggestion of "publishing the RESA provision in the AIP" in cases where a longer RESA might be desirable but could only be achieved by a reduction in declared distances. One could be excused for thinking that LTN might fit that description.