This appears to be one of the more borderline cases of "deception" and the use of paragraph 320(7a). Applicants are to be refused under paragraph 320(7a) where false representations have been made. There should have been a deliberate intent to deceive.
Even though your last refusal was almost 10 years ago, and therefore, it is plausible your omission could have been an "innocent mistake," The ECO's assessment of your deceptive intent is based on the following combination (it is likely that you could have been given benefit of doubt had it only been one of the two factors):
- You had appealed. This means you were more likely remember.
- You did not submit the passport associated with the refusal. The ECO thinks this was a deliberate attempt to decieve.
You should most definitely consult with a member of the UK law society to determine your future course of action(specifically with a firm that deals with deception in immigration cases). Non-action will affect your future chances of obtaining visas. You will need to show that you have a plausible innocent explanation for why you did not mention your refusal. In my opinion, this could be shown by:
- The fact that the refusal was almost 10 years ago. You could have simply forgotten that you had applied (this could be especially true if you had traveled to other countries extensively during this period). You could have miscalculated the dates--it was a matter of a few months. You remembered only 2017--not the exact month and assumed this meant 10 years had passed. You did not apply for almost 10 years. If you really wanted to hide your "deception" you would have simply waited a few more months.
- The new application process asks you if you have previous passports. However, unlike the old form, it only gives you the oppurtunity to include details of one previous passport. It could be argued, that this implies that the UKVI is only interested in "your previous passport" and not--since they haven't asked for details--your "previous passports."
However, only a practitioner in immigration law can tell you if there is a chance of success. The decision date on your refusal notice tells us that you applied using the old form where the history questions are limited to 10 years. On the new form the questions are unbounded by any time frame. Here's a screen shot...