It is not unusual for somebody to come to work in the UK and also to have significant responsibility for other parts of the group elsewhere in the world. It makes sense for him to have one contract for his UK work and another contract for his foreign work. In these circumstances, the foreign earnings (in respect of duties performed wholly outside the UK for a foreign employer) will be chargeable to tax on the remittance basis. If he were to have one omnibus contract covering the whole of his worldwide work, all the earnings would be fully chargeable to UK tax, notwithstanding that he may spend (say) two thirds (or more) of his time working overseas.
First published in Tax Journal on 7 February 2014