the night closures had little affect as most had re-scheduled and after 5 April the runway only closed after the last Monarch or Thomson flight had landed and that was between midnight and 2am depending on the night.
Were these closure times based on the scheduled times or the actuals? Not very good if you have to wait for an off schedule movement and have resources hanging around. Good reason for counter claims from the contractor.
And there's not a lot you can do in 4-5 hours, bearing in mind that you have to set up the worksite, do the work, ensure that the runway is safe for operation, break down the worksite, sweep and inspect the runway and have it ready.
If they've been waiting for off-schedule movements before starting out, no wonder they are behind.