We analyse a light charged Higgs boson in the 2-Higgs Doublet Model (2HDM) Type-I, when its mass satisfies the condition $M_{H^{pm}} < M_{t}+M_{b}$ and the parameter space is consistent with theoretical requirements of self-consistency as well as the latest experimental constraints from Large Hadron Collider (LHC) and other data. Over such a parameter space, wherein the Standard Model (SM)-like state discovered at the LHC in 2012 is the heaviest CP-even state of the 2HDM, it is found that the decay modes of the charged Higgs boson are dominated by $H^{pm} rightarrow W^{pm *} h$. Furthermore, the light neutral Higgs boson $h$ dominantly decays into two photons. Under these conditions, we find that the production and decay process $ p p to H^pm h to {W^pm}^{(*)} h h to l u_{l} + 4 gamma$ ($l=e,mu$) is essentially background free. However, since the $W^{pm(*)}$ could be largely off-shell and the $h$ state is very light, so that both the lepton coming from the former and the photons coming from the latter could be rather soft, we perform here a full Monte Carlo (MC) analysis at the detector level demonstrating that such a $W^{pm} + 4gamma$ signal is very promising, as it would be yielding significant excesses at the LHC with an integrated luminosity of $L=$ 300 $fb^{-1}$ at both $sqrt{s}= 13$ and $14 ~text{TeV}$.
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