A containerised generator set including: a container, and a generator; the container including: a body, and a pair of first doors; wherein, in a normal use position of the container, the body defines horizontal length and breadth dimensions and a vertical height dimension, and includes: a base extending in the length and breadth dimensions and defining a floor of an interior space of the body; a roof spaced apart from the base in the height dimension and extending in the length dimension between opposite, first and second ends (26, 27) of the body; and a pair of first and second sidewalls spaced apart in the breadth dimension, each of the sidewalls extending in the length dimension between the opposite ends (26, 27) of the body and in the height dimension between the base and the roof; the generator being arranged within the interior space of the body to exhaust cooling air via a first aperture at the first end or first sidewall of the body; the first doors being pivotably connected to the body for pivotal movement between a closed position and an open position, wherein in the closed position the first doors close the first aperture, and in the open position the first doors extend outwardly in the length or breadth dimension (L, B) away from said respective one of the first end and first sidewall (26, 23) of the body on either side of the first aperture; the container further including a removable wall, the removable wall being removably mountable in a mounted position between the first doors, in the open position of the first doors, to define between the removable wall, the first doors and the respective, first end or first sidewall of the body an upwardly open exhaust air duct external to the body; the exhaust air duct extending in the height dimension from a lower end region of the removable wall to an upper end region of the removable wall for at least most of a total height of the body; the removable wall being spaced apart from the body by the first doors from its lower end region to its upper end region in its mounted position. a container, and a generator; the container including: a body, and a pair of first doors; a body, and a pair of first doors; wherein, in a normal use position of the container, the body defines horizontal length and breadth dimensions and a vertical height dimension, and includes: a base extending in the length and breadth dimensions and defining a floor of an interior space of the body; a roof spaced apart from the base in the height dimension and extending in the length dimension between opposite, first and second ends (26, 27) of the body; and a pair of first and second sidewalls spaced apart in the breadth dimension, each of the sidewalls extending in the length dimension between the opposite ends (26, 27) of the body and in the height dimension between the base and the roof; a base extending in the length and breadth dimensions and defining a floor of an interior space of the body; a roof spaced apart from the base in the height dimension and extending in the length dimension between opposite, first and second ends (26, 27) of the body; and a pair of first and second sidewalls spaced apart in the breadth dimension, each of the sidewalls extending in the length dimension between the opposite ends (26, 27) of the body and in the height dimension between the base and the roof; the generator being arranged within the interior space of the body to exhaust cooling air via a first aperture at the first end or first sidewall of the body; the first doors being pivotably connected to the body for pivotal movement between a closed position and an open position, wherein in the closed position the first doors close the first aperture, and in the open position the first doors extend outwardly in the length or breadth dimension (L, B) away from said respective one of the first end and first sidewall (26, 23) of the body on either side of the first aperture; the container further including a removable wall, the removable wall being removably mountable in a mounted position between the first doors, in the open position of the first doors, to define between the removable wall, the first doors and the respective, first end or first sidewall of the body an upwardly open exhaust air duct external to the body; the exhaust air duct extending in the height dimension from a lower end region of the removable wall to an upper end region of the removable wall for at least most of a total height of the body; the removable wall being spaced apart from the body by the first doors from its lower end region to its upper end region in its mounted position.