So does that mean that the beneficiaries would put this on their TR but obviously no tax credit is repayable.
Yes; Box 2 on the SA107 2011.
I have just read in a TQT study text "Where the beneficiaries of a discretionary settlor interested trust distribute income to a beneficiary, the beneficiary is treated as recieving an amount of income equal to the net payment and the payment is deebed to be net of 50% tax. The payment is taxable as non savings income as the highest part of their income. The tax credit is not repayable.
The net of 50% applies to payments received on or after 6.4.2010 (40% before this date).
The receipt is non-savings income (ITA 2007 s 18). However, as such income is treated as the highest part of an individual's total income (s 685A(5A)) and the attaching tax is not repayable or creditable against any other part of an individual's income tax liability (s685A(4)(b)) it is perhaps academic that it is technically taxable.