  Stars which are rapidly rotating are expected to show high levels of activity
according to the activity-rotation relation. However, previous TESS studies
have found Ultra Fast Rotating (UFR) M dwarfs with periods less than one day
displaying low levels of flaring activity. As a result, in this study, we
utilise VLT/FORS2 spectropolarimetric data of ten M dwarf UFR stars between
spectral types $\sim$M2 - M6 all with $P_{\rm rot} <$ 1, to detect the presence
of a magnetic field. We divide our sample into rotation period bins of equal
size, with one star having many more flares in the TESS lightcurve than the
other. We also provide an analysis of the long-term variability within our
sample using TESS lightcurves taken during Cycles 1 and 3 (up to three years
apart). We identify 605 flares from our sample which have energies between
2.0$\times$10$^{31}$ and 5.4$\times$10$^{34}$ erg. Although we find no
significance difference in the flare rate between the Cycles, two of our
targets display changes in their lightcurve morphology, potentially caused by a
difference in the spot distribution. Overall, we find five stars (50%) in our
sample have a detectable magnetic field with strengths $\sim$1 - 2 kG. Of these
five, four were the more flare active stars within the period bins with one
being the less flare active star. It would appear the magnetic field strength
may not be the answer to the lack of flaring activity and supersaturation or
magnetic field configuration may play a role. However, it is clear the
relationship between rotation and activity is more complex than a steady
decrease over time.
