This is not quite correct.
Tax is certainly due on all income arising in the UK (pensions, property income etc.). In this case it appears, prima facie, that the income arises from work performed wholly outside the UK, so the income does not arise in the UK and is not subject to UK taxes.
This is the case, for example, where a UK business sets up a branch in, say, New York. Whether staffed by US personnel or UK personnel, all will pay taxes in the US.
This can be a complex area and it is vital that the contract is so structured that absolutely none of the duties of the employment are due to be performed in the UK.
The OP needs to be advised by UK accountants.