With that amount of money I would shop around the main high street banks. They will be biting his hand off! Recently, we had a lump sum of money (nowhere near the amount you are quoting) and it was in the bank no more than 24hrs and we were called in 'for a chat'! We listened to the options and went away and shopped around for a similar deal.
The highest interest will be paid where it can be locked for a period of time but if he wants instant access, the options will be less. However, he could lock X amount away and still have an amount for easy access.