A charge over receivables is, as indicated, a mere right to be paid out of the proceeds.
One way round this problem, which was used in family law until the enactment of the Human Rights Act 1998, was to apply principles which overrode mere rights, and could be used to determine the matter.
This is not a mere right of retainer, but rather courts in Australia have emphasised that it confers an equitable proprietary interest in those assets which has priority over the interests of the beneficiaries.
Naturally, a pledge over a chose in action is ruled out by the fact that the concept of possession is inapplicable to mere rights.
If a lender sells his mere right to interest for a lump sum the lump sum is received in exchange for, and ordinarily as the present value of, the future interest which he would have received.