"There are hundreds of thousands of holders of both UK and Irish passports.!
I'll be one soon :-)
"Yes unless you work for some government office as they will require you to surrender the Irish passport "
"You can work for the Civil Service in Britain with dual nationality:
You can apply for any job in the Civil Service as long as you are a UK national or have dual nationality with one part being British. In addition, about 75% of Civil Service posts are open to Commonwealth citizens and nationals of any of the member states of the European Economic Area (EEA). The remainder, which require special allegiance to the state, are reserved for UK nationals."