Thanks ChrisM@Work.

The query took quite some time to complete.

Additional info provided in case you need it.

ann_events_Tech_Details

[start_time] - clustered index

[id] - Unique, non-clustered index (PK)

ann_ReportItem

[source] - non-clustered index

[call_flow_name] - non-clustered index

[report_id] - non-clustered index

[id] - Unique, non-clustered index (PK)