For most purposes the morning peak, with its more expensive travel, is defined as 4.30 to 9.30 a.m., but in the case of Oyster Card single fares, the morning peak begins at 6.30. It is the less well-paid jobs that require people to travel before 6.30 (you still see men with their tool bags on the first Tubes of the day), so the generous impulse behind the working men's tickets has not entirely died out.