I get a lot job offers in my LinkedIn inbox and newsletters from places like glass door as I like to keep my eye on the market. One thing I’ve been seeing a lot recently is salaries for dev roles steadily dropping in the UK. The concerning thing, in my opinion, is that the poster linked by OP seems disillusioned as to the standard of living in the UK. They specifically mention being paid £55k as being equivalent to $…
I think you're missing some benefits. I don't know anything specific about this job offer and what would be on the paper offer, but UK public sector offers quite insane benefits compared to private sector, where salary might be like 50-60% of total compensation. Some I'm failiar with: free access to public nurseries (normal price was around £1200/monthy), 50% of costs for private high school, high retirement employer contributions, refunds for all public transport tickets used to get to work, access to gym, swimming pool, sauna, massage and therapies with max. 1 entry per day, free car parking during working days and weekends (otherwise £3-5 per hour), up to £100 per month for books - and this doesn't include annual training budget.
While the cash is quite low and won't get you far with luxury holidays abroad, it offers very high living standard in the UK.