Hi James,
This is a heart-felt `thank you` for everything you have done to secure my new position. Unusual amongst others in your role, your actions have been instrumental in achieving this and I am very grateful for your constant checking on the situation, negotiations, active updates and follow-ups to our conversations etc etc.
You have done me a great service and I hope I can justify your faith in me
Thanks again
Best regards,
G Griffiths