This appears to be a little different to the UKBA website document requirement detail on ILR:
The items of evidence should be from at least 5 different official sources. Ideally, a total of 20 items of evidence should be provided. If you are not able to do that, please provide at least 10 items.
Please give an explanation if you cannot provide at least 10 items and/or if the evidence is not in your joint names and/or it is not spread over the 24 month period as indicated. An explanation must also be provided for any periods when you did not live together, as well as evidence in support of the explanation and evidence to show how you maintained contact with each other during this time.
Your application could be delayed or even refused if you do not provide enough evidence of this kind.
telephone bills or statements
gas bills or statements
electricity bills or statements
water rates bills or statements
council tax bills or statements
mortgage statements or agreement
banks or building society statements/passbooks
tenancy agreements
insurance policies/certificates or other correspondence
loan agreements
AA,RAC or similar membership
membership of sports or social clubs
membership of a religious organisation
correspondence from government departments or agencies (eg HM Revenue and Customs, Income Tax, DHSS, DTI Work Permits) including evidence that you have declared your relationship to the appropriate government bodies.
correspondence from GP or local health authority (e.g. NHS card, correspondence about ante-natal and port-natal treatment, letter confirming dates of visits to the home address by a midwife, letter confirming registration with a dentist, etc – providing these documents show your home address and the date first registered)
