Redundancies account for two-thirds of all leavers

Resigning employees are most commonly expected to give one month's notice, but for redundancies, notice periods are more likely to be based on the statutory minimum, finds XpertHR research. 

Also

Survey: Managing employee departures, 2007 This survey covers policies relating to notice periods, compromise agreements, and confidentiality and non-competition clauses in contracts of employment. 

Labour turnover rates and costs: IRS survey 2010 Our research shows that employers experienced a voluntary resignation rate of 8.6% in 2009 - but this survey finds considerable variation in staff turnover rates according to region, sector and occupation. 

XpertHR employment law manual chapter on contractual rights on termination This explains the law on notice periods, including details on the statutory minimum periods that apply.