CHRISTOPHER STEVENS reviews last night's TV: Hidden away on Apple TV, the best comedy drama you've never seen

Little wonder children are growing up anxious. When five-year-old Stevie's school celebrates Earth Day, she comes home with a picture of a drowning polar bear and a phobia about leaving lightbulbs on.

It's no easier for their parents. 'Remember, take the electric car,' mum Karen (Sian Brooke) warns her husband, Scott (Darren Boyd), as she sends him off to the school gates. 'And for God's sake, don't mention how big this house is. Or holidays. Or anything else you might have boasted about before 2010.'

Trying, back for a fourth series on Apple's streaming video service, is almost certainly the best comedy-drama currently on TV that you've never seen.

It stars Esther Smith as Nikki, Karen's poorer, less snobby sister, and Rafe Spall as her amiably frazzled husband Jason — trying to cope with parenthood when they've barely got the hang of being grown-ups themselves.

Desperate for a family, Nikki and Jason turned their lives inside-out in the first three series, to be approved by adoption services. Now it's six years later and they're bringing up Tyler and Princess, whose birth mother disappeared when they were little.

It's an emotionally fraught set-up, and Trying can deliver lump-in-the-throat moments without warning — such as when Jason realises he is unable to talk to his own father (Phil Davis) about anything but football.

But writer Andy Wolton balances this with a stream of throwaway lines honed to comic perfection, scattered among a cast of top-name guest stars.

The first of these half-hour episodes centres on the funeral for Princess and Tyler's grandmother Bev, a brashly affectionate woman with a gleeful disregard for the law. Her final scam was to max out her credit cards, leaving a trove of goodies for the mourners at her wake. 'Is that an air fryer?' yelps Nikki excitedly.

The funeral service is a riot. 'If I could ask everyone to stand for Angels by Robbie Williams,' announces the vicar, who later reads the eulogy Bev has written for herself. It's a pack of lies.

At the booze-up in Bev's local, the publican (Paul Kaye, swivel-eyed as ever) warns people how to avoid upsetting the regulars: 'Don't look at Mikey. But if it does happen, don't look away first.'

In the second, Nikki has to contact the elderly lotharios Bev was dating, and ends up going ballroom dancing with the most wolfish of them, George (Jim Broadbent). When she tries to leave, he won't let her — 'My darling, my medication has barely kicked in.'

Better still, if you're new to Trying, there are 24 earlier episodes to catch up on. But for that, you'll need an AppleTV+ subscription which is a hefty £8.99 a month.

The real frustration is that Trying is made for Apple by BBC Studios, the Beeb's commercial arm. It's great that Auntie can still make shows as good as this when she tries . . . we'll just have to hope that this one eventually transfers to BBC1.