telling boss I've been offered another job

[teag1rl]

It's not the same as resgining-I will do that later as a formality, but at the moment I need to tell my boss that I have been offered another job before he receives a letter asking him for a reference!
Anybody got a nice way to put it. Do I just say 'I've been offered a job' or tell him to be expecting a letter asking for reference and go on from there?
This probably seems petty, but I've put it off long enough now-have to tell him today before a letter arrives!

[Loosehead]

Tell him you have applied for another job and to expect a request for a reference. You don't have to say you have been offerred it until you definately have the job, ie after the reference. Just say it's no reflection on this job it's just that you want to improve yourself. That way it may occur to him to offer you more to stay. No boss with any brains would take offence at another's endeavour.

[teag1rl]

Thanks Loosehead. It actually came about in conversation quite natuarlly as we were discussing job security etc. Good job I bit the bullet as when I collected post-there was the reference letter!

[SRH]

It's also perfectly acceptable to tell your new prospective employer that they cannot ask for a reference unless you are offered the job. This is standard practice in most jobs and means that your current boss only gets to find out you've been for interviews after you are definitely leaving - much less stressful. Good luck with your new job!