The aircraft was high on final approach and this was picked up by ATC using a tool called AFDAS (Approach Funnel Deviation Alerting System). The pilot was advised and then corrected and regained the normal glideslope. I don't know how close in this was, but maybe his higher descent rate to regain the glidepath was not fully corrected in time and he ended up a little low in the last hundred metres of the Approach.
The UK AAIB are investigating so we should see actual events in a report in due course.