Microwave background constraints on inflationary parameters

We use a compilation of cosmic microwave anisotropy data (including the recently-announced VSA results), supplemented an additional constraint on the expansion rate, to directly constrain the parameters of slow-roll inflation models. We find good agreement with other papers concerning the cosmological parameters, and display constraints on the power spectrum amplitude from inflation and the first two slow-roll parameters, finding in particular that $\epsilon_1 < 0.05$. The technique we use for parametrizing inflationary spectra may become essential once the data quality improves significantly.