This from the Ombudsman report covers that:
123. DWP has told us that direct mailing required planning and 2009 was the earliest possible start date. It explained it needed to engage with suppliers to get detailed costings on the preferred option, which involved working with private companies and ‘relatively new’ IT systems. It also says due diligence was needed because of the significant sums of public money involved. Even now, with modern IT, DWP says, a mailing would have a lead in time of months rather than weeks.
124. DWP used its *CIS database to identify women to write to. It told us CIS went live in March 2005, was piloted for the first year, and enhancements were made between April 2005 and June 2008 to make it a more comprehensive source of customer data. It said that citizen data was not robust before the introduction of CIS, and this only gradually changed once CIS was introduced. It told us that, given CIS was continually improving, ‘it would have been strongly preferable not to conduct a mail-out at least prior to 2008’.
* CIS means Customer Information Systems
I have some anecdotal evidence which would back this up.
When my husband died in 2007, I was entitled to claim a widow's bereavement payment and a widow's bereavement allowance for 12 months. These are based on a husband's NIC. My husband had paid Class 1 NIC for 40 uninterrupted years with two large employers. He was working until the day he died. DWP claimed he did not exist. They claimed they had no records for him under his name or his NINO. I sent P60s. They continued to argue for a whole year that no records existed for him. Eventually, I asked my MP to intervene and DWP paid up but despite several requests for an explanation, they refused to say what had happened.
In 2008 DWP were only two years away from implementing the WASPI changes but had no robust method of contacting every woman affected to tell her precisely how she would be affected.