Capturing Mary BBC2, 9pm Forgotten Heroes: The Not Dead Channel 4, 10pm

If you saw last week's long, slow, majestic Sunday-night drama by Stephen Poliakoff, Joe's Palace, you saw many of the same elements of his latest long, slow, majestic Sunday-night drama, Capturing Mary .

Both these self-consciously important works were, for instance, set in the same place: a lavishly-appointed but mostly uninhabited mansion located in one of central London's classier burghs. There, Poliakoff chose to give a second week's employment to the old house's wise fool of a caretaker, young Joe, again imbued with brusque social ineptitude by Danny Lee Wynter.

In addition, Capturing Mary echoed Joe's Palace in focusing on a character who was engaged in a desperate attempt to make amends for a grim, unfulfilled present by more fully understanding their own despoiled past. Weighty stuff. Monumentally expressed.

At great length.

By characters who thought way too much about doing things. Sometimes via silence. Sometimes in brittle chuntering. Before eventually deciding not to do those things. Slowly. Sheesh . . .

And in just the same way as Joe's Palace, it wasn't until you were very close to the agonised, artfully-prolonged conclusion of Capturing Mary that you worked out what in heck the whole palaver had been about. Almost.

So what was Capturing Mary about? It was about a formerly trenchant journalistic wunderkind and social commentator, Mary Gilbert, who was seeking to assuage her own guilt at having long ago betrayed her talent to serve the truth via a needless act of fearful compromise. Probably.

Crucially, you see, Mary had enjoyed occasional glittering soirees at the lavishly-furnished London house during her gilded youth's first flowering in the 1950s. On one haunting evening back then, however, poor Mary had let her career be fatally blighted in the mansion's scary wine cellar by a singularly sinister figure. Think of Noel Coward crossed with Coronation Street's wormy weasel, David Platt, and you are only halfway to satanic gossipmonger Greville White.

Greville was played by Matt Lucas's comic sidekick in Little Britain, David Walliams. But when you gazed into Greville's basilisk eyes, you didn't think of comedy.

What those unsettling eyes revealed was casual wickedness. All-knowing and hellhole black they were. Evil Greville. Well done, Walliams.

A langorous lounge lizard, Greville dedicated himself to deftly whispering words of unspeakable cruelty into well-connected ears, thereby undermining creative confidence or de-railing lives.

"Your latest doesn't seem to have caused quite the same stir as your last," Greville murmured fatally into one film-maker's lug hole.

Shortly afterwards, he was casually poisoning poor Mary's own sweet, innocent ears with tales of horrific acts of degradation routinely perpetrated on helpless victims by archbishops, politicians, film stars.

Mary should have aired these hideous revelations in writing to serve the public good, but didn't. Because she'd promised Greville she wouldn't. For reasons she didn't fully comprehend. Her life was ruined by Greville White, the ghost of a ghost who wasn't really a ghost.

As young Mary, Ruth Wilson was a crimson-lipped corker (despite having a pout on her to eclipse that of Donald Duck). As old Mary, Dame Maggie Smith was broken, red-eyed, maddened.

Similar visages could be seen elsewhere last night, victims of post-traumatic stress disorder. Forgotten Heroes: The Not Dead featured one old and two not-so-old British soldiers bidding to escape hellish memories forged on battlefields from Malaysia to Iraq over the past 50 years.

When not seeking to exorcise their past, they spoke Simon Armitage's poetry. "We're morbidly ill soldiers/ With nothing but time to kill." Close to Remembrance Day, it was good not to forget them.