Valid from date when trading licenses

My wife is driving on a full Chilean license which she received back in 2006. She is driving in the UK with it during the 1 year grace period, but must transfer to a UK license by January 2019.

However, with her UK license (a provisional for now), the "Valid from" is now going to be 2018 and as such, her insurance cost is much, much higher than with her Chilean license.

Does anyone know if upon passing the UK test, the UK license can somehow be back dated to when her Chilean license was received which indicates that she's not actually a new driver. Seems crazy that the same person cost hundreds more to insure one day to the next because they receive a UK license.