The new dressing gowns every year and designer pyjamas for children was bizarre. There's probably not a child in the land of the ages of those in this family (except possibly pre-teens in super super wealthy families) who will appreciate the extra cost of such items.
Same with expensive Christmas baubles. I do fully understand them wanting to make Christmas magical for the DCs, but children would get just the same magic at probably a tenth of the cost.
Their house might have been huge, but house prices in Barnsley are comparitively low - it could easily have cost them around £2-300k (also prices took years to get back to pre crash levels even when south east prices were racing ahead) so if they benefited from London price increases and buying and selling at the right times, they could have had savings into six figures.
Maybe their previous careers had also been well paid, and they'd saved money too, so were effectively 'retired' SAHPs? I assumed that, as well as living off savings, their income was DLA for the older twins, plus payments for fostering, although they did say that they'd also adopted the babies, so they wouldn't be paid, but they also mentioned fostering other children too?
A lovely family, but very odd approach to spending. Ten trees? Stupidly expensive everything when 'normal nice' is plenty, new Christmas decorations, dressing gowns and bedding repeatedly - I wonder what they do with all the old things? I only buy things like that every 5/10/20 years and it would just not occur to me to buy new every year.
But in the end, this programme is about the real excessive cases, but it does seem odd that the people featured don't seem to realise that their way is not 'normal' and they need to be shown how average people spend their money.