OK rationale coming up. The sell back of days in lieu for OCT averaged out at £820 per day. A DIL could be accrued by spending a whole day at NERC or even just travelling down there on a day off. I don't think it is reasonable to compare this type of buy back of time directly with an additional operational duty at LATCC.
I also don't think that a non-op additional duty at NERC as an instructor should have the same rate as the operational duty.
These are only my own feeling on figures and are based on NATs level of desperation, but I feel that the rate should be around £550-£600 for the DIL and non-op duties and around £950-£1000 for the operational duties.
It is imperative that the price for additional operational duties be too high for them to become the norm or there will be no incentive to resolve the crisis.