Help LG G2 SMS number prefix thread issue

[Android Question]

I have migrated my text messages from Sony Z1 to an LGG2 F320 and I'm noticing that messages from the same number have created 2 threads. Although the contacts from which messages are being received have a local UK number 07XXX-XXX-XXX the messages in one thread are from this number, the other thread has the number +44 7XXX-XXX-XXX ???
This is so annoying as the previous handset had no such problems with the same recipients. Is there a setting I have to change ? I've checked my google account and it is set to my country being UK.

I have searched online for a solution but cannot find any. Please help.

 

[Guggy]

Have you synced your messages to your SIM card? That may be causing it.