Effect on credit score

I have been slow stoozing for a while now, building up a debt on an interest-free credit card, and saving the money instead. A few months ago I realised that old-style Stoozing was now worthwhile again, when I discovered a no-fee money transfer offer in my (little-used) MBNA account. I applied for several 0% balance transfer credit cards and used the MBNA card to transfer money to my bank account. I now have a total 'stooze pot' of £33k, with the money invested in various current and savings accounts paying at least 2%.

However, in the process my Experian score has plummeted from 999 to 663. This is not a source of worry, as I am retired and own my home outright, but I would like to apply for further 0% credit cards in due course and build up my stooze pot still further.

My question is whether my Experian score is likely to improve in the near future, as I have not made any further credit applications recently, or will it continue to stay at a relatively low level because I have such a large debt (despite having savings to pay it off in full)?

Any information from experienced stoozers would be welcome.