If you hand it in at the bank, get a receipt. Not all bank's client account or segregation of funds policies are up to scratch. There's no point in subsidising the Bank Managers "Paddy Power" account (or assuming cos you are honest, they are too).
If you still want those Mavics, you could (I suppose) return the funds via route of the casino (in true investment banker fashion). Should you make a handsome return you could repay funds in full (plus receive a tasty set of Mavics), less operating expenses and a handsome bonus for being so clever. Should you loose the monies en route, you could always claim out of pocket expenses accrued anyway (which would be tax deductible should you be a Tory party donor or domiciled in a tax haven).