If you had applied for a Returning Resident Visa and it was not granted (merely being "reconsidered") then there is no way you would have been allowed into the UK.

The entry clearance officers at UKVI initially decided that you didn't qualify for the visa, having had all the time they needed to look at the facts of your case. They were apparently in the process of reconsidering it, but by travelling to the UK you were effectively asking the immigration officers to sidestep the entry clearance officers and make a decision there and then. If this is correct, then you shouldn't be surprised that the immigration officers declined to make a decision and denied you entry.


I am told that Returning Resident visas are notoriously difficult to get. You need to see an immigration solicitor and it is not legal for anyone other than OISC-registered immigration advisors to give advice on visa applications.