Someone has set up an account in my name

fourmarks

If he has successfully opened an account in your details then he now has the opportunity to open further accounts, obtain loans, credit cards etc and run up all manner of debt in your name. Perhaps he has already started to do so. The consequences of that could be become extremely complicated, inconvenient and, of course, expensive. I suggest you take steps to stop this asap, and follow the sensible advice given above by Rob5342.

TheBanker

You need to tell the bank because can be held responsible for the account. If you don't tell the bank now that you have knowledge of the account then you can be seen as complicit in whatever crimes are being committed. If the account is being used for fraudulent purposes or to launder the proceeds of crime, this can have long term consequences for you so you need to act immediately. However tempting it may be, you must not withdraw any money from this account. The bank should freeze it while they investigate and will ultimately return the money to its rightful owner. 

Personally I would be applying for a CIFAS Protective Registration marker (https://www.cifas.org.uk/pr) to stop this person from opening any more accounts using your details. As the poster above highlights, they would probably be in a position to be able to apply for loans or credit cards using your details, which could cause a whole world of trouble for you. 

If your passport is missing you need to report it as lost or stolen: https://www.gov.uk/report-a-lost-or-stolen-passport

I'd also be obtaining my credit reports from all three Credit Reference Agencies and checking carefully for unknown accounts,  unexpected credit searches or unexpected financial associations which could imply further fraud by this person. This article tells you how: https://www.moneysavingexpert.com/loans/check-free-credit-report/. Bear in mind that you need to look at the actual accounts and searches listed in the report. Ignore the 'score' calculated by the CRA. 

Make sure all your accounts are updated to your new address to reduce the chances of this person obtaining further documentation. Don't rely on the Royal Mail to redirect mail as it sometimes goes wrong. 

If there is any possibility that this person could know any of your banking, email or social media passwords, then change them immediately. I would also suggest telling your main bank that you have been a victim of identity theft. 

As for what else to do, it depends on your relationship with your mother and this person. Does your mother have a solicitor dealing with her divorce? If so I would probably seek their advice.

James

The Bankers advice is good with one exception.   CIFAS Protective Registration,

Consider MyPAS instead which is a lot more effective than CIFAS Protective Registration, costs nothing, zilch to put into  place. and reaches all creditors who view your Credit Files, not just CIFAS members 

More info here. A Solution to Identity Fraud.

Good luck.

TheBanker

James said:

The Bankers advice is good with one exception.   CIFAS Protective Registration,

Consider MyPAS instead which is a lot more effective than CIFAS Protective Registration, costs nothing, zilch to put into  place. and reaches all creditors who view your Credit Files, not just CIFAS members 

More info here. A Solution to Identity Fraud.

Good luck.

The OP can make his own choice, personally I would stick with CIFAS despite the cost, because it is what the banks recommend. I have evidence (which I have access to through my work) that CIFAS PR prevents fraud. I have not seen any evidence that the MyPas solation is effective.