Not sure where this 7 year reference comes from but naturalisation is based on meeting the residence requirements for either 5 years or 3 years (married to spouse BC). The absences limits are :
Residential requirements
To demonstrate the residential requirements for naturalisation, you must have:
* been resident in the UK for at least five years (this is known as the residential qualifying period); and
* been present in the UK five years before the date of your application; and
* not spent more than 450 days outside the UK during the five-year period; and
* not spent more than 90 days outside the UK in the last 12 months of the five-year period; and
* not been in breach of the Immigration Rules at any stage during the five-year period.
The link below explains when discretion is applied
http://www.ukba.homeoffice.gov.uk/briti ... cesfromuk/