During the period in the bridgehead and until the armies had crossed the SEINE, the organisation of the L of C remained largely unchanged from the original layout. There were, however, one or two minor alterations involving local administrative changes of L of C formations.
On 31 July HQ L of C assumed responsibility for the control of CAEN through 7 Base Sub Area, which relieved 101 Beach Sub Area there.
On 3 August, 10 Garrison at PORT EN BESSIN was relieved by 101 Beach Sub Area and reverted to under command Second Army.
By the end of August, 102 Beach Sub Area became 6 L of C Sub Area and on 28 August 12 L of C Area took over direct responsibility for CAEN from 7 Base Sub Area.
Meanwhile preparations were being made for establishing the advance base in the area NORTH of the SEINE and 7 and 8 Base Sub Areas were standing by ready to implement at the earliest opportunity the original plan whereby they would administer the SEINE ports under HQ L of C.
It became apparent, however, after the crossing of the SEINE and the rapid advance into BELGIUM, that the L of C would be stretched to its utmost and that the advance base would be established in the area of ANTWERP and BRUSSELS and not in the area of LE HAVRE.
As a result many changes were effected on 2 September 12 L of C Area took over from 11 L of C Area administrative control of all L of C formations in the bridgehead and subsequently assumed responsibility of all territory SOUTH of the SEINE within the boundaries of 21 Army Group; on 3 September 11 L of C Area moved forward to AMIENS and took over administrative control of the BRITISH sector of FRANCE NORTH of the SEINE to the FRANCO-BELGIAN frontier.
This territory was divided into two departments, SEINE. INFERIEURE and PAS DE CALAIS, which were administered by 6 and 15 L of C Sub Areas respectively meanwhile 7 and 8 Base Sub Areas had moved into BELGIUM and were responsible for ANTWERP and OSTEND respectively, whilst 4 L of C Sub Area administered the area of BRUSSELS.