Tolly said:

"Flexible cable has been used to wire installation which is a departure from BS EN 50565-1:2014".

However, 7671 permits the use of flexible cables in fixed wiring, as discussed in issue 95 of Wiring Matters. 

Just because BS 7671 permits the use of flexible cables, it doesn't mean they are suitable for use everywhere and anywhere.

Without further information (i.e. specific circumstances of the use of the cables), no-one can say whether the EICR coding is correct or not (although Code C2 is quite serious, one would assume it's a real problem??). Specifically, BS EN 50565-1:2014 says;

• (4.4.5) Flexible cables shall not be used as fixed wiring unless they are contained in an enclosure affording mechanical protection, with the following two exceptions:
   - final connection to fixed equipment when the duty type of the cable is at least ordinary duty or higher;
   - fixed installations in temporary buildings when the duty type of the cable is heavy duty.
  But BS 7671 does not define 'fixed wiring', nor does BS EN 50565-1, and nor does IEC 60050 ... and 4.4.1 of BS EN  50565-1 requires flexible cables to be used to connect mobile equipment (is this 'fixed wiring' ... who knows?). To be fair, BS 7671 does define 'fixed equipment' (and since wiring is electrical equipment, I suppose that might do). Again, caravans seem OK wired in H03 and H05 ?
  
• (4.4.6) Flexible cables shall not be installed in plaster
•  (4.4.10) Thermoplastic covered cables shall not be used for welding, this includes both industrial arc welding and hobby welding.
  Although my arc welder came with a thermoplastic mains cable fitted ... so it's OK for the equipment, not the installation?
  
• (4.4.11) Flexible thermoplastic cables are not suitable for permanent use outdoors.
  Although H05VV-F seems to be supplied with most caravans and motor homes and seems to do OK ... but I guess it's not "permanent"??

As Graham mentions, the choice of  H coding of cable types can be important, and it can cause confusion to the unwary - but there is a pattern and I find a table similar to this one  to be helpful. Note that Neoprene (PCP PolyChloroPrene) and PVC PolyVinylChloride both generate nasty fumes in a fire, but PCP is much tougher against abrasion and cuts, and also lasts much better under UV light than PVC - which is usually cheaper.  Thermally both are very much the same, so current ratings are unchanged.

As Graham mentions, the choice of  H coding of cable types can be important, and it can cause confusion to the unwary - but there is a pattern and I find a table similar to this one  to be helpful. Note that Neoprene (PCP PolyChloroPrene) and PVC PolyVinylChloride both generate nasty fumes in a fire, but PCP is much tougher against abrasion and cuts, and also lasts much better under UV light than PVC - which is usually cheaper.  Thermally both are very much the same, so current ratings are unchanged.