[Brian Bines]

The Home Office weekly reports give the following enemy aircraft reported over the UK in the period :-

14/15th June Single aircraft dropped bombs in E.Anglia
15/16th June ten enemy aircraft over the UK during attacks by Flying Bombs
19/20th June brief land fall by enemy aircraft at Dover and Dungeness
20th evening two enemy aircraft over east Scotland and one over Scapa Flow
20/21st June two enemy aircraft over E.Anglia
22/23rd. June five intruders over E.Anglia
23/24th June One enemy aircraft over Orfordness destroyed by a NightFighter ( Ju188 of I(F)/122 crashed near Woodbridge Suffolk)
From 0600hrs. on 28th June to 0600hrs on 5th.July no enemy aircraft reported overland.

Any chance your mother in law may have remembered the crashed Do217 on 14/15th (not 19/20 as previous ) March near Friston (crew all killed), and the later June claims were for aircraft approaching the coast and claimed as shot down in the sea. There was a lot of luftwaffe activity over the Channel in June against Allied shipping and the aircraft claimed may have approached the UK coast (mining) without planning to fly inland.
I believe file AIR16/173 held at the Public Records Office Kew may contain brief details of AA claims in 1944,