In case you may be interested. I was asked the following question which I sent to the British Embassy in Madrid.

"If a person is a Resident of Spain, can they only return to the UK for a maximum period of 90 days out of 180?"

This was the reply:

"Hi Alan, That will depend on the nationality of the person who wishes to travel to the UK.

The 90/180 days limitation rule replies to UK nationals who wish to travel within the Schengen area. This does not include the UK.

There is a limitation to the amount of time you can spend out of Spain, from the point of view of maintaining your residency in Spain."

For further residency questions, please see:UK Gov. Advice : Living in Spain