This is what you get if you decouple reward and results

Anyone who has worked in a non-unionised private sector job is liable to spray coffee at their screen when they read what civil servants who work over 36 hours a week can do:

A growing number of officials are understood to be working nine-day fortnights by cutting short their lunch breaks and extending normal hours by staying in their offices until 6pm. Civil servants are also allowed to count delays in arriving for work because of late trains or traffic congestion towards their contracted working week.

Until 6pm! Those poor slave-driven creatures. The irony of London Underground Government employees reducing the hours worked of other London-based Government employees is delicious. Unless you're the poor schmuck paying taxes to fund this.

We shouldn't be surprised at this. It's the natural consequence of the fact that there's a very loose connection between civil servants' presence in the office and the practical output of their department. It's even possible that there is a positive result for the tax payer, in that the natural tendency of office-based Government employees is to obstruct and destroy practical productivity by the rest of the nation; few indeed are the non-vocational Government employees whose hours in the office make a positive contribution to the nation's GDP.

The Civil Service’s "flexitime" document, which covers the working conditions of tens of thousands of officials, says that "with the exception of the senior Civil Service, all staff are eligible to work flexitime".
It says that the standard working week is 36 hours in London and 37 hours outside the capital. This means the standard working day is slightly longer than 9am to 5pm, with an hour for lunch.

May I quote Dilbert: "Work can be very rewarding; you should try it."