Madagascar is a French stronghold, though not for long. The Franco-Hova Wars occurred just as IOTL, and the island's monarchy is abolished though most of the princely families are still around. Despite repeated invasion attempts by the Cape Colony and Natal, Madagascar is protected by a small Franco-Italian naval squadron that still has enough bite to keep British forces on their toes.Not to add more work, but what's going on with Madagascar in this timeline?
On land, the French governor-general has convinced many Malagasy locals to oppose the British, arguing how their arrival would set in place the discriminatory administrative system already at play across the Cape and Natal (while conveniently white-washing French discrimination elsewhere). As a result, many locals are less than forthcoming to the British Expeditionary Forces.