Apologies for the late reply - with Xmas and so on I've only just seen this. That said,
I suspect you're familiar with neither the scope nor scenarios and clients that Government Gateway services. Verify only does SAML. No ADFS/WS-* (so no support for the NHS, for example), no Chip & PIN (both Identify and Respond, on Java and .NET silicon -- this is important because provisioning), and assorted side-scenarios required by the security cluster.
The idea of a verification company is laughable. Forgive me.
Digital identity systems must be designed so the disclosure of identifying information is limited to parties having a necessary and justifiable place in a given identity relationship (see law 3 of the laws of identity, https://www.identityblog.com/stories/2005/05/13/TheLawsOfIde...).
What justifiable role does a bank or credit agency play when I require meds for an STD? Amongst some very, very personal and private transactions some of us make? A credit agency's purpose is to provide a credit rating, and not to verify identity.
Also note that many banks and credit verification agencies GDS proposes are HQ'd outside the EU, which makes Verify impossible to use by many organisations in the UK - and can therefore never replace the Government Gateway.
Verify's technical shortcomings can be built out and addresed. The use of commercial, unjustifiable verification companies with poor security records to boot (Experian, HSBC, and so on) cannot. This is Verify's single biggest failing.