The overall cost of absence from work for the year 2004 is an estimated £12.2bn, a sum covering the cost of meeting salaries for absentees, the resulting overtime and temporary cover, and lost service or production time.
The CBI / AXA Absence Survey of over 500 organisations found:

6.8 working days were lost per employee in 2004;
the total number of days lost to absence across the UK economy fell by 4.5% to 168 million in 2004, from 176 million in 2003, although rising labour costs and growth in earnings meant the total cost of absence increased.
Public sector
According to the CBI / AXA Absence Survey, rates of sickness absence across the public sector are on the retreat, down from 10.1 days per person to 8.5.
In defence of the public sector performance relative to the private sector, HSE points out that, from its own survey (SWASH), there are features of public sector employment that place it at a disadvantage when this comparison is made, for example:

organisational size is a major influence on workplace absence, with rates of absence higher in larger rather than in smaller organisations - for organisations employing more than 5,000, the difference in performance between the public and private sectors is small;
gender differences - women (on average) take more sickness absence than men and the public sector employs a higher proportion of female workers; and
older employees have more sickness absence than younger counterparts and the public sector has an older workforce than the private sector.
Comment:
"Workplace absence and productivity are high profile issues. They affect our competitiveness and productivity as a player in a global economy. They can be used to indicate how well an organisation is managed. And, not least, they have an impact on individuals in the workforce - their health, well-being and motivation.
The Task Force's work is supported by the Government's Health, Work and Wellbeing Strategy, which aims to break the link between ill health and inactivity, advance the prevention of ill health and injury, encourage good management of occupational health and transform opportunities for people to recover from illness while at work, maintaining their independence and sense of worth." - Chair of the Ministerial Task Force on Health, Safety and Productivity.
"Short-term absence caused by genuine illness isn’t a problem for those employers who run their business well and create a positive workplace environment where employees are encouraged to give it their best shot. Long-term absence on the other hand is better tackled by early intervention and active case management. Indeed, employers who provide their people with early access to medical care and rehabilitation have lower levels of absence." - AXA Head of Corporate Healthcare Development.
"Employers understand that staff are not invincible. They accept that the majority of absence is due to genuine minor illness and nobody is saying genuinely ill staff should drag themselves to work. But let's be honest about this - there are some employees out there who will gladly award themselves a day off when they are in good health at the expense of their employers and hard working colleagues.
With summer almost upon us, employers may well be concerned about staff granting themselves days off that they are not entitled to. Organisations suspect that staff 'pulling sickies' cost the UK economy £1.7bn last year alone, a bill we simply cannot afford to pay in today's fiercely competitive global market." - CBI Deputy Director-General.