In this paper, we investigate to what extent labour market institutions influence the way firms respond to flexibility requirements in terms of human resource management. In order to do so, we consider two contrasting economies: France and the UK. France is highly regulated, whereas the UK is more clearly a ‘liberal market economy’. We focus on the food processing sector which is subject to very similar competitive pressure in both countries. Our methodology is based upon plant-level case studies. We explore numerical and functional labour flexibility in terms of outcomes at the firm level. How and to what extent are firms able to deliver flexibility in different institutional contexts? Does this matter in terms of outcomes for workers? We find evidence that firms use a combination of different forms of numerical flexibility although there appears to be a slight move away from internal flexibility (overtime) to external flexibility (agency workers) in the UK and possibly in the opposite direction in France. The research also seems to suggest that there is not a simple trade-off between numerical and functional flexibility. In France, the organisation of work indicates a more functionally flexible core, with a less skilled, numerically flexible periphery. However, in the UK there is little evidence that firms are utilising the core workforce in a similar way. Part of this may be due to the more stable workforce found in most of the French plants. But perhaps more importantly, this is likely to be due to the high cost of labour in France which creates an incentive for firms to replace many of the lowest skilled jobs by machines.