After the conquest, Rome got access to and control of some very important trade routes. This brought in a lot of business and in turn wealth to the people of Rome . This was what caused a new class of wealthy Romans to emerge.
One reason could be that since England has colonized most of the countries in the past, the English language has been spread around. Another reason would be since English speaking countries like the US and Britain are powerful economically, knowing English is very important when making trades and business deals.