Yes, I'm afraid it probably will.
The flow measures were agreed late LAST YEAR (Nov, I think) and publicised here. NATS management have continually played down the impact of the introduction of Swanwick. You'd have to ask them WHY.
The operational controllers (like Me) need some time to get used to the new equipment and procedures and for safety's sake, we need to keep the traffic levels down until be get some experience and confidence in the new kit. You might gather from this that our training on the new system has been somewhat basic.
Sorry for the delays, it gives me no pleasure to hold any aircraft on the ground longer than absolutely necessary, but please understand it's for your own safety.
Rgds BEX