  The lack of power anomaly is an intriguing feature at the largest angular
scales of the CMB anisotropy temperature pattern, whose statistical
significance is not strong enough to claim any new physics beyond the standard
cosmological model. We revisit the former statement by also considering
polarisation data. We propose a new one-dimensional estimator which takes
jointly into account the information contained in the TT, TE and EE CMB
spectra. By employing this estimator on Planck 2015 low-$\ell$ data, we find
that a random $\Lambda$CDM realisation is statistically accepted at the level
of $3.68 \%$. Even though Planck polarisation contributes a mere $4 \%$ to the
total information budget, its use pushes the lower-tail-probability down from
the $7.22 \%$ obtained with only temperature data. Forecasts of future CMB
polarised measurements, as e.g. the LiteBIRD satellite, can increase the
polarisation contribution up to $6$ times with respect to Planck at low-$\ell$.
We argue that the large-scale E-mode polarisation may play an important role in
analysing CMB temperature anomalies with future mission.
