What were the 'Big Four' railway companies in the UK before nationalisation
The Big Four were London, Midland and Scotland (LMS), London and North Eastern Railway (LNER), Great Western Railway (GWR) and Southern Railway (SR)
Below is an instruction that describes a task, paired with an input that provides further context. Write a response that appropriately completes the request.
### Instruction: What were the 'Big Four' railway companies in the UK before nationalisation
### Input: 
### Response: The Big Four were London, Midland and Scotland (LMS), London and North Eastern Railway (LNER), Great Western Railway (GWR) and Southern Railway (SR)