from the OP:
I'm on downwind, preparing to turn base but I am aware of an A/C on final which I cannot see.
As others have said, try asking the other aircraft where they are? (Assuming radios fitted)
There is always the option, if you lose SA (or never had it) on other circuit traffic, to leave the circuit entirely, both laterally and vertically and rejoin later. It probably won’t be much of a difference in eventual landing time. Throwing in random orbits, excessively long downwind legs and/or going through the overhead at circuit height appears to be more likely to lead to conflicts, if you read the UKAB reports...