I worked for Transco, National Grid Transco and National Grid for nearly 10 years and was able to pursue my career positively for the majority of the time. The apprenticeship and graduate schemes can be very good and several of my former colleagues were successful in following either of those routes and have had a lot of fantastic opportunities.
Personally, I found my career stalled at manager level after over eight successful years. I seemed to hit a ceiling – not based on my capability… That proved very frustrating. However I built on the skills, capabilities and excellent opportunities I had gained there to continue to progress my career elsewhere. On balance the frustration has been more than countered by the great roles and people I worked with there and the foundation it provided.
Hope this helps?