it was todo with their link/care for the working class (generally doing manual labour etc in industrial britain) they appeal to this "lower" class and thus took on the name Labour.

It takes less labour and time to produce certain products using machinery than using manual labour.

They had to do hard manual labour, such as quarrying.

Manual work/labour is physical work done by people.

Manual labour (manual labor in American English) or manual work is physical work done by people, most especially in contrast to that done by machines.