"James Agate, a critic famous in his day, wrote, ‘either the murderer was Wallace or it wasn’t. If it wasn’t, then here at last is the perfect murder.’
Let’s start with what we know.
We know that at the time of the murder Wallace was terminally ill. He’d spent a month as an in-patient in a Liverpool hospital in mid-1930 and had it made clear to him that his remaining kidney was diseased and malfunctioning and that nothing could be done to reverse or even arrest that. We also know he was a deeply introspective, introverted, and cerebral man. Wholly self-taught, his interests covered chemistry, science in general, philosophy, chess, music, and literature – interests that, together with his psychological traits, tended to cut him off from those among whom he lived and worked.
We know, and this knowledge is only about fifteen years old, that Julia Wallace was nearly twenty years older than her husband and yet had got away with claiming to be the same age as him. No one at the time suspected it. She did not look her age. She had lied persistently on official documents about her age, parentage, place of birth and even her first name, and did so too with her marriage certificate. We know she rented and did not own the house she lived in when she met Wallace. We know she had today’s equivalent of £2340 in her Post Office account and on the night she was killed about £40 in cash in a pocket applied to the inside of her corset. She would have had to undress to get at the money.
We know that when Wallace arrived home from his wasted trip to Mossley Hill in pursuit of business from Mr Qualtrough, he was able to enter his back yard through the door in the wall. He said he’d told his wife to bolt it after him. If she had, he wouldn’t have been able, or expected, to get in.
We know that Julia was killed around 8pm. Professor McFall wrote that in the first report he made to the CID. He later changed his mind although he had no better evidence than he had had when he made that first report.
And finally we know that, contrary to PD James’s theory, Wallace did not cost Parry his job by reporting him to the Pru for paying-in less than he collected. It was more than a year after Wallace caught Parry out that Parry left the Pru of his own accord. About a month before the murder, Parry gave Wallace a calendar from his new employer. It was Wallace’s supervisor who told him later that Parry’s father had made good shortages in his son’s accounts.
So, given what we know, what might have happened? Someone killed Julia and with a degree of violence of which Wallace, given his temperament and physical condition, was probably incapable. What’s more, whoever it was did it when Wallace was several miles from home. Someone who was let into the house by Julia; someone she either knew or thought she knew. Someone who intended from the start, or was provoked, to kill her. Someone from her distinctly strange past, perhaps, or someone who wanted her out of the way? Or someone who was persuaded, rewarded, or pressured to kill her so someone else could benefit? Someone else who might then feel that at the end of a lifetime of frustration and disappointment he (or she) had organised ‘the perfect murder’".