Steve HS-KPG arrived at Stansted on 5 May (16:05 approx) and departed to Guernsey using its Thai registration as callsign on 23 May (12.30 approx). For almost all of the time it was at Stansted it was in the Gulfstream Service Centre hangar.
It returned from Guernsey on 26 May (about 19.30) as N69GA and departed to the USA at 08.30 on the 27 May.
from the above it appears to have been physically repainted/re-registered in Guernsey. Not having seen it personally, perhaps on of our Guernsey correspondents can confirm the paint change.