*UPDATE*
After many days arguing with BT my customer support finally got them to admit Interleaving actually had not been turned off like they said it had, it was immediately turned off and my pings have returned to normal.
IDNet must have the best customer support out there.
Pinging
www.bbc.co.uk with 32 bytes of data:
Reply from 212.58.224.86 bytes:32 Time:28ms TTL:249
Reply from 212.58.224.86 bytes:32 Time:30ms TTL:249
Reply from 212.58.224.86 bytes:32 Time:29ms TTL:249
Reply from 212.58.224.86 bytes:32 Time:29ms TTL:249
Reply from 212.58.224.86 bytes:32 Time:28ms TTL:249
Reply from 212.58.224.86 bytes:32 Time:30ms TTL:249
Reply from 212.58.224.86 bytes:32 Time:29ms TTL:249
Reply from 212.58.224.86 bytes:32 Time:30ms TTL:249
Reply from 212.58.224.86 bytes:32 Time:29ms TTL:249
Reply from 212.58.224.86 bytes:32 Time:28ms TTL:249
Reply from 212.58.224.86 bytes:32 Time:29ms TTL:249
Reply from 212.58.224.86 bytes:32 Time:29ms TTL:249
Reply from 212.58.224.86 bytes:32 Time:31ms TTL:249
Reply from 212.58.224.86 bytes:32 Time:29ms TTL:249
Reply from 212.58.224.86 bytes:32 Time:28ms TTL:249
Reply from 212.58.224.86 bytes:32 Time:28ms TTL:249
Reply from 212.58.224.86 bytes:32 Time:29ms TTL:249
Reply from 212.58.224.86 bytes:32 Time:28ms TTL:249
Reply from 212.58.224.86 bytes:32 Time:28ms TTL:249
Reply from 212.58.224.86 bytes:32 Time:29ms TTL:249
Reply from 212.58.224.86 bytes:32 Time:28ms TTL:249
Reply from 212.58.224.86 bytes:32 Time:28ms TTL:249
Reply from 212.58.224.86 bytes:32 Time:28ms TTL:249
Reply from 212.58.224.86 bytes:32 Time:28ms TTL:249
Reply from 212.58.224.86 bytes:32 Time:28ms TTL:249
Reply from 212.58.224.86 bytes:32 Time:29ms TTL:249
Reply from 212.58.224.86 bytes:32 Time:29ms TTL:249
Reply from 212.58.224.86 bytes:32 Time:28ms TTL:249
Reply from 212.58.224.86 bytes:32 Time:27ms TTL:249
Reply from 212.58.224.86 bytes:32 Time:29ms TTL:249
Ping statistics for
www.bbc.co.uk :
Packets: Sent = 30, Received = 30, Lost = 0 (0%) loss),
Approximate round trip times in milli-seconds:
Minimum = 27ms, Maximum = 31ms, Average = 29ms