Apologies Baz,
In addition to Royal Mail, we only use Parcelforce and DPD. Earlier you mentioned that Parcelforce is crap, so we used DPD this time.
At present we and a small percentage of our customers are finding delivery delays from all carriers. We are trying our best, using premium services. The diversion switching from 2nd to 1st class, or 1st class to courier, or switching from one courier to another has cost us 11% over and above what we would normally pay. This is not a moan or sob story. I am just explaining what we at ARC are doing to deal with the situation. We are getting goods out as quickly as we can. For Royal Mail, there will be strike dependent delays in transit – currently between 1 to 2 weeks for 1st class depending on U.K. destination, regardless of what you buy from all shippers who use Royal Mail.
There is higher pressure on the carriage system at present due to execution of Black Friday deals, and strikes which are outside our control. Certain large corporates are switching from the cheapest e.g.EVRI to other carriers, and then from Parcelforce to carriers like DPD when Parcelforce is on strike. This has put an increased load on DPD… as in our case, and it is clear that they are all having difficulties coping. It’s a case of crap rolling downhill!….
This afternoon as I write, just been advised… don’t use DPD for shipments to Stoke or Cardiff as their depots are well and truly backed up and will need senakot to relieve their constipation … Parcelforce on strike today….so we are removing such parcels from the system now, and will switch them over to Parcelforce on Monday!
Yes, the result is that we are hearing about these problems every day, and we are switching between services as and when we hear about expected problems with a service or destination area. Had we participated in Black Friday deals, our problems would have been greater. 
Ketan at ARC