For someone just starting out then I agree it's a fantastic opportunity, for a grad it'd be great as the lower banding salary is far from horrific fresh out of uni and will set you up very well for the future.
But for an existing professional in this field it's not an attractive offer, although to be honest I don't think that's the sort of people they want. Think they want the young fresh out of uni types personally.
The thing is a lot of these will be tempted to work for a bank on twice that salary. A lot of the very smart kids I graduated with went to Quantitive Analyst type positions etc.
As I said previously , I appleid for GCHQ after Uni, was invited for an interview, and then just realised that it was being massively underpaid and I also changed careers directions (doing a PHD and getting paid 10-15K more than at GCHQ). I also had 2 interview lined up for investment banks in London who would be paying 15K more .
Money is not that important to me but I don't like to feel that I am being underpaid.
Also to put things in perspective while searching for jobs in the US recently I had hundred of hits form US DoD and intelligence agencies (NSA etc.), I would be looking at $150,000 USD (except im not american and wouldn't want to anyway). That is about £100K sterling fo doing a similarjob in the US.
My girlfriend in a totally different field but in Academia had the same thing. She had an offer from a good University in England, salary expects in the lower £30K, she accepted an offer from a top US University an earns 3x times that in a 9 month work year with half the required teaching hours.
Hence academia in the UK is going down the pan.
Now guess why I doubt i will ever work in the UK again.