Inclusion Criteria:  Male or female between 18 and 89 years of age inclusive at the time of consent with Karnofsky score of 50% or more at screening Male or female ≥90 years of age at the time of consent with Karnofsky score of 70% or more at screening Diagnosis of Bullous Pemphigoid either newly diagnosed or relapsing Patients with confirmed atypical Bullous Pemphigoid Bullous Pemphigoid classified as either moderate or severe on the basis of the Investigator Global Assessment (IGA) at randomisation Willing to receive immunisation against Neisseria meningitidis and/or antibiotic prophylaxis Provision of voluntary written informed consent  Exclusion Criteria:  Patients with recalcitrant BP that have never achieved CDA or who have never been in complete disease remission despite long term treatment with super potent topical steroid or oral cotricosteroid Epidermolysis bullosa acquisita, mucous membrane pemphigoid, or anti p200 pemphigoid Mucosal lesions BPDAI score accounts for ≥30% of total BPDAI activity score at randomisation BP considered to be drug induced, in particular diagnosis of BP made within two months of starting a drug well known to induce BP Treatment with BP-directed biologics including: a) Any cell-depleting agents including, but not limited to, rituximab within 12 months prior to baseline, b) Other biologics within five half-lives (if known) or 16 weeks prior to the baseline, whichever is longer, or c) Intravenous immunoglobulin within 16 weeks prior to the baseline. Taking > 0.3 mg/kg/day OCS at screening Treatment with systemic immunomodulators such as dapsone or doxycycline within four half-lives of the drugs prior to baseline Day 1 Treatment with immunosuppressants within the last two weeks prior to baseline Treatment with an anti-complement therapy or with Zileuton within the last three months prior to baseline OCS dose no more than 0.3mg/kg/day in the 7 days before screening visit Taking super-potent topical corticosteroids and unable to discontinue them at or before the screening assessment Active systemic or organ system bacterial or fungal infection or progressive severe infection Known congenital immunodeficiency or a history of acquired immunodeficiency including a positive human immunodeficiency virus (HIV) test Active infection with hepatitis B or C Positive nasal throat swab for Neisseria species Known hypersensitivity to nomacopan and any of its excipients Receipt of live attenuated vaccines within 2 weeks of Day 1