Thanks for your interest, Red. To keep you and others posted:
I wrote to Ancestry advising them of the problem, and received the following very unsatisfactory response:
"We appreciate your message.
I have looked at your account and see that you have generously shared your tree with quite a few people. It may be that these two people received an invitations inadvertently. If you are concerned about the privacy of your account you may try changing your password. I can see no reason why they would have received invitations unless they were sent from your account.
If there is anything else with which we might assist you, please let us know."
I have therefore written back to them accordingly:
I find your response to my query both unsatisfactory and patronising.
Please escalate and investigate.
In summary, to repeat for your information
I am a long term subscriber to Ancestry, with an annual subscription
I have a Private Tree
I received, yesterday, emails from you notifying that three people - *, *, and * - had accepted an invitation from me to see my Private Tree.
I advised you that I had not invited any of these people, and they are completely unknown to me, and requested your urgent investigation.
I do not expect to receive a response from Aaron of Members Solutions telling me a) that I have invited a number of people (yes, I know, they are family connections) and b) that he can see no reason for the invitations to these people unless I had done so myself.
The evidence that I have not invited these people is that I have told you I have not.
In addition, I found * shown on my list of people with whom the tree was shared, and I had to remove the name three times before it disappeared from my list, a fact I also advised you.
Please therefore note that I am reporting a serious and important problem, and I require a serious response.
How have these people been invited, since I have not invited them;
why did it take several attempts to remove lachta from the list of shared people:
and what assurance to you have that this error is not going to be repeated?
I await your response.
Many thanks
* Moderator's Comment: details of Ancestry members removed