E-commerce in plaintext - I can see that working well
Instead, what he probably means is he wants the power to read unencrypted data at rest held by providers (e-mail/IM/website/ISP/etc) via a government login used by government departments and a robot Theresa May feriously rubber stamping a pile of paper 24 hours a day, 365 days a year. End-to-end encryption banned, everything must be held in plaintext by the provider, GPG etc... text blocks automatically rejected.
Just so this isn't the UK pissing in the wind it might become a condition of trade within the EU and maybe the US/Canada/Aus/NZ. I think the UK are chairing some EU-wide security committee round about now and there's always TTIP for the English speaking world.
Must adjust my tinfoil hat.