I have found a solution to removing the spurious entries. Its not instanteous, but it will be a lot less tedious than rebuilding accounts from last uncorrupted backup. I document here, in case it happens to someone else.
As already stated, the spurious entries appear in reports, cash flows, but not in the registers. They have come from the recurring transactions or "bills" part of Money after a crash during startup. They appear in savings, checking accounts and cash part of investment accounts. The report enries will not delete, nor can I edit edit amount, date and account.
1) The key to this method was realising that when I do a download from an online account Money offers the spurious entries to match with the download as well as "real" ones. If you select and accept the spurious ones as the match (not the real one) then Money converts the spurious into a "real" one which appears as normal in the register (eg my current account).
2) This can then be edited normally. I then end up with two real entries in the register but I simply have to delete the unreconciled one.
3) The only issues are a) that some of the spurious entries are annual subscriptions and would only be downloaded for matching in 11 months time (the reports will be in error till then) and b) some spurious entries will not be downloaded for match because the subscriptions get cancelled or there is a payment holiday for some reason.
4) However, when downloading and matching the online account , I can select any spare online account entry, unmatch it from its correct match and match it any of the unmatched spurious entries in the list. I then accept it and Money converts the spurious to a real one which matches the date and amount to downlaoad in the register. It means that I then have to do some careful editing in the register to make everything add up. This means deleting the "converted" spurious entry in the register and then manually reconciling the entry that was originally matched by Money. The result is that one less spurious entry.
5) I have cleared one savings account of spurious entries and it no longer has a warning from Money when I open it. The savings account total in accounts summary page matches the register account. I still have 9 spurious entries in the current account (down from over 20). They total up to exactly account for the error on the account page as compared to real total in the register. I am confident the method works. I just have to wait until I have 9 new transactions downloaded in my account, but that will only take 2/3 weeks not 11 months. I could encourage my wife to spend some money on the account and generate some transactions quickly, but I am too tight for that!
Best wishes