From the Unite Absence at work handbook here:
http://www.unitetheunion.org/pdf/Job...ide%20pgv2.pdf
It discusses the differences between statutory sick pay and occupational sick pay. For statutory sick pay:
An employer must provide its employees with details of their sick
pay entitlement as part of the written statement of employment
particulars. Many employers provide an occupational sick pay
scheme that is more generous than statutory sick pay (SSP).
To claim statutory sick pay the employee must notify their
employer. The employer may have its own notification procedure
but it cannot insist that the employee notifies them in person
nor insist on a doctor’s certificate for the first seven days of
absence for this purpose.
But for occupational sick pay, which I believe BA provides:
Some employers will provide an occupational sick pay scheme.
The scheme must pay at least the equivalent of statutory sick
pay. As occupational sick pay schemes are a contractual
entitlement the employer can set its own rules and guidelines.
My bolds
So from this it seems that for SSP an employer cannot insist on a doctors note for the first 7 days, but if an employee wishes to take advantage of the enhanced benifits of OSP they have to follows the T&Cs that the employer has laid down. This may include sick notes required for any sick period during time of industrial action.
regards