On this evidence, the battle of the whodunnits is already won

TBut brothers Jack and Harry Williams insist it was an accident, not a publicity stunt, that their latest co-written six-part crime serials, Liar (ItV) and Rellik (BBC1), started at the same moment on the same day, on opposite channels.

millions of fans are addicted to the convoluted plots that are a speciality of this duo, creators ( together) of the sensational abduction thriller the missing.

Problem is, you can’t watch two Williams Whodunnits at once.

So which did you watch, and which took second place to be seen later?

the obvious solution was to watch Rellik on the Beeb and record Liar, so you could whizz through the adverts. But as is usually the case with a Williams Bros puzzle, the obvious answer was the wrong one.

Liar delivered instant gratification. the concept is instantly gripping and the headline stars generate a chemical reaction together so strong, it’s atomic.

Joanne Froggatt — who rose to fame as long-suffering mrs Bates, the lady’s maid in Downton Abbey — has a gift for conveying dangerous undercurrents, all sweet smile

MOUTHFUL OF THE NIGHT: Have more words ever been crammed into half an hour than by Ben Elton in his Shakespeare sitcom, Upstart Crow (BBC2)? Lickspittle nincombunion and dunceling clumbletrousers were some of the shorter ones.

and mad eyes. Here, she plays teacher Laura, desperate to vent some frustration as she stumbles out of a sterile relationship.

Laura went canoeing at dawn in wild estuary marshland. When a bloke at the boat club paid her a clumsy compliment, she looked ready to disembowel him with her paddle.

then into her life strolls mr Fantastic. He’s a surgeon with million- watt teeth and hair so good it’s probably got its own Hollywood agent.

Ioan Gruffudd, who plays the charismatic medic Andrew, is best known for super-hero movies such as the Fantastic Four. In Liar, he is wealthy, widowed and a devoted single father, he’s almost too perfect. Why isn’t he surrounded by gasping groupies, begging to be bedded and wedded?

However, Laura is convinced that during their first date, he drugged her wine and raped her.

Andrew denies it airily — insisting to the police that they had consensual sex and it was great.

most viewers might tend to believe Laura — if it wasn’t for the guarded reaction of her friends and family. there’s something in this woman’s past: ‘Do the police know what happened last time?’ asks her brother-in-law.

this is a crime without evidence. there’s no CCtV, no forensics, almost no physical clues at all.

our suspicions swing from Laura to Andrew and back again, based on nothing but the tone of a voice or a hesitation before an answer. Brainpower won’t help you unravel Liar. this crime demands all your emotion and intuition.

Rellik is very different. It’s the hunt for a serial killer, told in reverse (Rellik is ‘killer’ backwards). When we first see traumatised detective Gabriel markham (Richard Dormer), he has already wrapped up the case. the story backs up in leaps and bounds, to the arrest, and before that the final murder. the idea is that after six episodes, we will understand what happened and why.

But the effect is like doing 3D sudoku in your head. It’s so baffling that your only hope may be to watch in groups, the tV equivalent of book clubs. every couple of minutes, press the pause button and ask each other: ‘Who is he? How do they know each other? Where are those two going?’

I trust the writers to explain every answer, eventually. But I have serious doubts about my intellectual capacity to understand a word of it. He twist is so improbable, the coincidence so colossal that you’d think the writers must have planned it this way from the start.