Guardian - UK middle classes ‘struggling despite incomes of up to £60,000 a year’

quady - No... place the context of "essentials" within the context of modern society and a UK average standard of living.
People who choose to spend their substantial incomes on lots of discretionary luxuries (large expensive high performance motor vehicles, large houses far in excess of the norm (remembering that large houses in turn cost much more to maintain, heat) pets with large monthly bill, etc... etc...) could create a comfortable headroom simply by cutting back on the discretionary luxury spending. Plus the hedonic treadmill effect means that very quickly these luxuries stop feeling like luxuries and your back where you started, except this time chasing an even more expensive luxury for the thrill...
It's a bit of a myth that all high earners "should" or do live it large in mansions with range rovers etc.... lots of people on high/large/huge incomes are very much "millionaire next door" types who live comfortably by not living excessively - in normal(ish) houses, with normal(ish) cars. They save a lot to give plenty of financial headroom in case bad times roll around, or to retire early.
If you continually increase your spending to match your income level because of a perceived belief that thats what wealthy people do (encouraged greatly by the marketing departments of companies who sell luxury goods!) well.... no income will ever be enough.

OK...
Is there a list of these "essentials" within the context of modern society and a UK average standard of living?

A quick google search will bring up lots of useful hits that might assist - the Joseph Rowntree Foundation and various other bodies do plenty of work in this area.
As a starter for a average household, I'd be looking at something like:

I'm sure there's a couple of extras to add but that's probably a good starter.

OK everyones situation is different and we don't know exactly whats's going in the lives of the people quoted in the article, but the most detailed example in the article near the end was pretty illustrative that the debt in this case wasn't caused by a poor salary, just lots of spending on discretionary luxury goods.
Eg: Matthew on £73,000 - earnings that place him easily in the top 10% of all earners (+ not living in London helps him further)
Quote from the article:
Monthly overheads add up, including £110 for property service charges, £550 for petrol, £240 for council tax, £300 for electricity, £200 for car insurance, £370 for dog day care, £170 for special diet dog food, £90 for mobile phone bills, and £200 for life insurance. After all these costs there is little left to enjoy life, says Matthew, whose daughter currently still lives at home.
“I’ve cancelled the gym membership, and we’re lucky if we’re going out once a month. It’s increasingly difficult to make ends meet and repay this debt.”
Again, we don't know everything about Matthew's life but that a lot of spending that Matthew has chosen to make. It doesn't say what his car is but based on £2,400 a year for car insurance & £550 on petrol a month it's a fair assumption we're into serious luxury SUV/sports car territory here. £300 a month on electricity is over double (not far off triple) the average household energy bill (so I think there would be some easy jumper and sock related savings here!). Then £550 monthly on costs for his dog... well we all like what we like, but again it was a choice to take on the responsibility of owning and looking after an expensive pet. On the mobile phone front a sim only deal would be much cheaper.
Matthew complains he doesn't have enough money to enjoy life... but he does, he chooses to spend it on the enjoyment of:

Jesus, just shows how deprived I was in my 20s living in a one bed with no car.

Except that Matthew's mother has advanced dementia and is cared for by his father, who has a heart condition and poorly controlled diabetes. When Matthew's work moved 60 miles away, he had to stay in his home, close to his parents. So he pays for his father's and a private helper's phone contracts, as well has his own, to make sure they all have data, and unlimited minutes etc. He has a high insurance on his car because he drives a gazillion miles per year on his commute and last year had his car vandalised twice. He rescued a dog from the local pet rescue, and now finds it has a long term health condition which costs a fortune, and his Dad can no longer look after it when he's at work.
In other words, s**t happens to people regardless of income. Deciding to look after your parents, or drive a safe car, or look after a beloved pet is a 'choice' in exactly the same way as choosing to have children or follow a faith.

I couldn't see references to all of this in the article, was there a follow up piece about Matthew I missed that you could link me to? (and its a bit odd that this pretty important context wasn't mentioned in the piece at all)
Even with this - the point is the Matthew still earns in the top 10% of earners, there will be people on average household incomes of c£35,000 (and lower) who are also looking after elderly parents/juggling long commutes and all the other trials life throws at us. He has much more financial resources to accommodate this than most, and I genuinely can't work out why he's paying for his own fuel for a 60mile travel to a new project site that would almost certainly be expensible.
On the final point.... choosing to take on responsibility for a pet is a choice, and perhaps given Matthew's significant responsibilities to his parents and existing time constraints with his job and commute perhaps also taking on responsibility for a pet wasn't the wisest choice? Ditto you don't need an expensive car to buy one with a high safety rating, economy hatchbacks like a 3 year old Skoda Fabia have 5 star best in class ratings for safety.

My info about Matthew is theoretical. The point is that no matter what your income, the proverbial can hit the fan for anyone, and a large salary doesn't protect you from challenges.
Btw, you can't claim expenses for normal travel to work, if your office moves location, and you can't move, than you are left with the cost. And he got the dog before his paren't health declined. You also don't throw away money you have invested in a vehicle just to buy a more efficient one. All you are showing with this detail is that you haven't actually lived this experience, you just view life as numbers - it really isn't. By your reckoning, if everything can be solved by being more financially efficient, there'd be no poor people living in London, they'd all move out and commute in or work elsewhere. But they don't, because they have networks and communities and a thing they call 'home' which is more than just any old set of 4 walls and a roof. Same for Matthew on his 74k or someone on 140k