Bankruptcies are searchable going back far more than 6 years (London Gazette archives I think).
But IVAs are not. As far as I'm concerned, once it leaves the records it's expunged and you are under no obligation to declare it.
And indeed that's how it was explained to me at the start by my IP.
Here's the basis for my opinion (beyond being told by my IP).
A criminal record, in many cases, will become "spent" after a time, giving you a legal right to say "no" even when directly asked if you have a record.
But an IVA must be forever declared condemning perhaps a person to a life of no mortgage, no competitive credit, no job in finance EVER... Does that sound right to you?
If it must be declared forever, why is it deleted from the credit file? Why does it not remain there forever?
Why does it get deleted from the insolvency register rather than being marked "Previously insolvent"?
There are claims that if you failed to declare it on a mortgage application and the bank later found out they could repossess the house. Well, if they didn't find out when they did all the checks at the start, what makes you think they'd somehow find out later? Why would they even go looking? If they did, why would they trash a profitable mortgage that's being payed regularly and go through a hugely expensive repossession and risk ending up with a loss?
But hey, this is just my interpretation and opinion (plus what I was told). Do feel free to counter it of course
I know a lot do disagree with me!