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We present a novel pilot search for gravitational lenses in the mJIVE-20survey, which observed $24\,903$ radio sources selected from FIRST with theVLBA at an angular resolution of 5 mas. We have taken the visibility data foran initial $3\,640$ sources that were detected by the mJIVE-20 observations andre-mapped them to make wide-field images, selecting fourteen sources that hadmultiple components separated by $\geq100$ mas, with a flux-ratio of$\leq15$:$1$ and a surface brightness consistent with gravitational lensing.Two of these candidates are re-discoveries of gravitational lenses found aspart of CLASS. The remaining twelve candidates were then re-observed at 1.4 GHzand then simultaneously at 4.1 and 7.1 GHz with the VLBA to measure thespectral index and surface brightness of the individual components as afunction of frequency. Ten were rejected as core-jet or core-hotspot(s)systems, with surface brightness distributions and/or spectral indicesinconsistent with gravitational lensing, and one was rejected after lensmodelling demonstrated that the candidate lensed images failed the parity test.The final lens candidate has an image configuration that is consistent with asimple lens mass model, although further observations are required to confirmthe lensing nature. Given the two confirmed gravitational lenses in themJIVE-20 sample, we find a robust lensing-rate of $1$:($318\pm225$) for astatistical sample of 635 radio sources detected on mas-scales, which isconsistent with that found for CLASS.

A novel search for gravitationally lensed radio sources in wide-field VLBI imaging from the mJIVE-20 survey