I guess (s)he means https://en.m.wikipedia.org/wiki/Stability_and_Growth_Pact:

"The fiscal discipline is ensured by the SGP by requiring each Member State, to implement a fiscal policy aiming for the country to stay within the limits on government deficit (3% of GDP) and debt (60% of GDP); and in case of having a debt level above 60% it should each year decline with a satisfactory pace towards a level below"

Though the UK is not bound by those rules anyway, so still not a great example:

"The only EU member state being exempted to comply with this MTO procedure is the UK, as it per a protocol to the EU treaty is exempted from complying with the SGP. In other words, while all other member states are obliged nationally to select at MTO respecting their calculated Minimum MTO, the calculated Minimum MTO for the UK is only presented for advice, with no obligation for it to set a compliant national MTO in structural terms."

I assumed that the [they] related to the previous government, although the EU did pass measures which essentially outlawed Keynesian economic solutions.

The Stability and Growth Pact would be hard to enforce in the UK, not least because Germany didn't even follow it itself.