  We present the study of cross-correlation between Cosmic Microwave Background
(CMB) gravitational lensing potential map released by the \textit{Planck}
collaboration and photometric redshift galaxy catalogues from the
\textit{Herschel} Extragalactic Legacy Project (HELP), divided into four sky
patches: NGP, \textit{Herschel} Stripe-82, and two halves of SGP field,
covering in total $\sim 660$ deg$^{2}$ of the sky. We estimate the galaxy
linear bias parameter, $b_{0}$, from joint analysis of cross-power spectrum and
galaxy auto-power spectrum using Maximum Likelihood Estimation technique to
obtain values ranging from $0.70 \pm 0.01$ for SGP Part-2 to $1.02 \pm 0.02$
for SGP Part-1 field. We also estimate the amplitude of cross-correlation and
find the values spanning from $0.67 \pm 0.18$ for SGP Part-2 to $0.80 \pm 0.23$
for SGP Part-1 field, respectively. For NGP and SGP Part-1 fields the amplitude
is consistent with the expected value for the standard cosmological model
within $\sim 1\,\sigma$, while for \textit{Herschel} Stripe-82 and SGP Part-2
we find the amplitude to be smaller than expected with $\sim 1.5\,\sigma$ and
$\sim 2\,\sigma$ deviation, respectively. We perform several tests on various
systematic errors to study the reason for the deviation, however, value of the
amplitude turns out to be robust with respect to these errors. The only
significant change in the amplitude is observed when we replace the
minimum-variance CMB lensing map, used in the baseline analysis, by the lensing
map derived from the CMB temperature map with deprojected thermal
Sunyaev-Zeldovich signal.
