US stock options

When this issue first arose I thought i knew the answer but after speaking to HMRC i'm now more confused than before!

My client works for the UK subsidiary of a US company. As part of his package, he receives US stock options exercisable at certain time for an agreed price. In 20011/12 he exercised some of his USstock options and immediately sold the shares on the US stock market for a gain.

His employer has confirmed that no tax (either UK or US) was withheld on the cash proceeds he received.

I now need to put he details on his 2011/12 tax return.

i was expecting that PAYE should have been operated by his UK employer and NICs should have been payable. I rang HMRC but they tell me NICs aren't payable and i should put the details on the foreign  income pages not the Additional Info where i was expecting to report it.

Could anyone confirm the position for me?

many thanks