Details on entry routes onto Apprenticeships can be found in the Apprenticeships Evaluation: Learners survey report online. The survey comprised a representative sample of 5,000 apprentices. https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/387662/bis-14-1208-Apprenticeships-Evaluation-Learners-December-2014.pdf
In 2013/14, two thirds (64%) of apprentices worked for their employer before starting their apprenticeship. This has decreased since 2012/13 when it was 68%.
In 2013/14, nine out of ten (91%) apprentices aged 25+ worked for their employer before starting the apprenticeship, compared with 29% of apprentices aged 16-18 and 60% for those aged 19-24. Women are more likely to be internal recruits (72%) than men (54%).
Further breakdowns can be found on page 23 of the above report. This information is not included in our routine data collection and hence data is not available since 2010. Information is not available for entry routes by constituency.