How fish are helping hippos, and lizards are lions’ best friends; Prince Philip’s home movie footage of the Queen and other members of the royal family. Plus, the penultimate episode of Line of Duty
Nature’s Perfect Partners: Natural World
What does a tortoise do when it can’t scratch its itch? Find a finch to peck its ticks. This documentary examines the reciprocal deals that go on in the animal kingdom, where creatures help each other with everyday tasks. Bill Bailey expertly narrates stories of hippos being exfoliated by hungry fish, lizards snacking on the flies that buzz around sleeping lions, and a sloth whose fur is home to algae, whose colour provides a handy camouflage. Fascinating. Hannah Verdier
Elizabeth at 90: A Family Tribute
Doubtless you’ll have your own plans for celebrating the Queen’s 90th birthday. But if you find yourself indoors you could do worse than tune into this commemorative celebration, drawing on Elizabeth’s own collection of home movies shot by hubby Philip. They feature a cast of characters including the Queen Mum and the Queen’s father, George VI. Meanwhile, family members, including Charles, Harry and Anne, reminisce fondly and frankly about Her Maj. David Stubbs
Line of Duty
It’s just office politics, to begin with. “Dot” Cottan v Steve Arnott, with Kate Fleming shifting her affections, junior staff as pawns and Ted Hastings, the boss, trying not to be played. So the penultimate episode has more of the infuriating “It’s him! Why can’t you see it’s him?” story upon which this season has been too reliant. But writer Jed Mercurio is too smart and too tricky to simply leave it at that. One crackling interview scene and some rapid developments later, and we’re hurtling towards a cliffhanger a mile high. Jack Seale
Aliens: The Big Think
The question of whether we are alone in the universe is one that’s occupying some of the greatest scientific minds of our times. So says Professor Martin Rees, the Astronomer Royal and no mean thinker himself, who points out that researchers increasingly think we live in a galaxy where Earth-like planets, many teeming with life, are commonplace. But what stripe of aliens should we be looking for? Let’s try hunting for machines rather than organic life, suggests Rees. Jonathan Wright
British Army Girls
9pm, Channel 4
In the last in the series, the troop returns from its Christmas break for a final four weeks of its most challenging training yet, using the skills the women have learned under combat conditions. There may be some issues along the way. Krystal needs to stop acting as the class clown and start taking things seriously, while former art student Megan needs to plumb down and find the self-confidence to prove her detractors wrong and pass out as a soldier. Ben Arnold
Shakespeare’s Legacy with John Nettles
On the 400th anniversary of Shakespeare’s death, RSC alumnus John Nettles takes us gently by the arm and steers us through Stratford, to explore the bard’s life and legacy – and “lost years”. What was he up to before he moved to London? Gallivanting through Italy? Or touring the countryside with the Elizabethan equivalent of the Legz Akimbo theatre company? Truly, it’s a mystery to tax the brain of Bergerac. Ali Catterall
Thicker Than Water
Being caught lying is awkward at the best of times. But for Liv, after being caught with her metaphorical pants en flambé by Oskar, it soon becomes clear that the stakes are a little higher than pretending you have no idea who left the lid off the milk. Lasse is hardly behaving as a paragon of virtue, either, as his reluctant descent into the underworld accelerates. This latest in C4/All4/More4’s seemingly neverending supply of darkly compelling Swedish dramas continues to captivate. Mark Gibbings Jones
Lawless, (John Hillcoat, 2012) 11.05pm, Film4
More rough stuff from the director of the post-apocalyptic The Road and the Oz outback western The Proposition. Loosely based on a true story, it’s set in 1931 Virginia, where Tom Hardy and Shia LaBeouf lead the Bondurant clan in their moonshine business until a corrupt, sadistic fed (Guy Pearce) starts muscling in. Relentlessly violent. Paul Howlett
The Fog, (John Carpenter, 1980) 1am, ITV4
This murky chiller from horror master Carpenter has a menacing fog drifting in from the sea against the prevailing wind. Wrapped up in it are the ghosts of mariners, looking like rejects from Pirates of the Caribbean and not at all benevolent to the good people of Antonio Bay. Among the supernaturally threatened are Janet Leigh and Jamie Lee Curtis. PH
Women’s Super League: Arsenal v Chelsea,5.30pm, BT Sport 1
The champions visit Meadow Park.
Premier League Football: Arsenal v West Bromwich Albion,7pm, Sky Sports 1
Arsenal look to firm up a place in next season’s Champions League.
Premier League Darts, 7pm, Sky Sports 2
Round 12 action in Bournemouth.
Rugby League: Wigan Warriors v Huddersfield Giants, 7.30pm, Sky Sports 3
Super league clash.
This article was written by Hannah Verdier, David Stubbs, Jack Seale, Jonathan Wright, Ben Arnold, Ali Catterall, Mark Gibbings Jones and Paul Howlett,, for The Guardian on Thursday 21st April 2016 06.10 Europe/London
guardian.co.uk © Guardian News and Media Limited 2010