Chiltern Railways were great, and were one of the few TOCs that genuinely competed for passengers against other railways, as Chiltern, Virgin (now Avanti) and London Midland (now West Midlands / London Northwestern) all operated competing services between London and Birmingham.
Back in the day, Chiltern had express peak-time services to Birmingham which were only marginally slower than Virgin's high speed trains. But Chiltern was much cheaper and would serve you a cooked breakfast and proper espresso coffee at your seat - in standard class!