I've worked 24 hour shifts. They can be fun! (I turned down the most recent offer of one though. 24 hours locked inside the secure area of a Metropolitan Police station, noting the movement of vehicles going in and out, simply didn't appeal to me!)
The answer to Welshtanner's question about whether it's legal or not (in relation to Ratter's work, not mine) is simply "No, it isn't!".
The law doesn't limit the length of a shift but it does require a minimum 11-hour break between the end of one day's work and the start of another. So Ratter's working hours are illegal unless:
(a) he starts work progressively later each day, to ensure that he gets an 11-hour break ; or
(b) he's self-employed (in which case he's free to determine his own working hours).