  Context. Most stars form in clusters or associations but only a small number
of these groups are expected to remain bound for longer than a few Myr. Once
star formation has ended and the molecular gas around young stellar objects has
been expelled via feedback processes, most initially bound young clusters lose
the majority of their binding mass and begin to disperse into the Galactic
field. Aims. This process can be investigated by analysing the structure and
kinematic trends in nearby young clusters, particularly expansion, the
tell-tale sign that a cluster is no longer gravitationally bound but is
dispersing into the field. Methods. We combine Gaia DR3 5-parameter astrometry
with calibrated radial velocities for members of the nearby young cluster
{\lambda} Ori (Collinder 69). Results. We characterise the plane-of-sky
substructure of the cluster using the Q-parameter and Angular Dispersion
parameter. We find evidence that the cluster contains significant substructure,
but that this is preferentially located away from the central cluster core,
which is smooth and likely remains bound. We find strong evidence for expansion
in {\lambda} Ori in the plane-of-sky using a number of metrics, but also that
the trends are asymmetric at the 5{\sigma} significance level. with the maximum
rate of expansion being directed nearly parallel to the Galactic plane. We then
invert the maximum rate of expansion of 0.144^{+0.003}_{-0.003} kms^{-1}pc^{-1}
to give an expansion timescale of 6.944^{+0.148}_{-0.142} Myr, which is
slightly larger than typical literature age estimates for the cluster. We also
find asymmetry in the velocity dispersion, potential signatures of cluster
rotation, and calculate kinematic ages for individual cluster members by
tracing their motion back in time to their closest approach to the cluster
center.
