Good post Steve! I've posted the same kind of thing, but David won't see the obvious, that Sheila had been dead for hours. I like his table though 
Not only do the reasons for a possible delay not apply to Sheila how about you actually read what is posted
Most authorities agree that lividity attains its maximum intensity, on average, at around 12 h postmortem, but there is some variation in descriptions of when it first appears, and when it is well developed, i.e. confluent. Hypostasis begins to form immediately after death, but it may not be visible for some time. Ordinarily its earliest appearance, as dull red patches, is 20-30 min after death, but this may be delayed for up to 2, or rarely 3 h. The patches of livor then deepen, increase in intensity, and become confluent within 14 h postmortem, to reach a maximum extent and intensity within about 6-10 h, but sometimes as early as 3 h or as late as 16 h. Faint lividity may appear shortly before death in individuals with terminal circulatory failure. Conversely, the development of lividity may be delayed in persons with chronic anemia or massive terminal hemorrhage.Even if post mortem hypostasis was delayed in a "rare" situation of 3 hours. That gives another 3.5 hours for it to develop still. Not to mention that the causes for a delay do not apply to Sheila but they do in June and hers is clearly visible. What Steve has posted is actually shooting him in the foot.
Plus with the 7.5 hours benchmark I am being very generous to the prosecution here. This gives Jeremy very little time to finish engineering the scene then to peddle is arse pronto in the night back home over the fields then to clean himself up and do the final acting rehearsals. A more reasonable time frame would be 8.25 hours.