Sapper -
From the baptism information for Jacques I have his details as transcribed -
10.3.1811 Le Brocq Jacques fs Phle fs Jean fs Phle et Jeanne Le Maistre
(i.e Jacques is the son of Philippe, who is son of Jean who is the son of Philippe, and Jeanne Le Maistre)
There are loads of other Le Brocq's from St Ouen - and there are still many there today!
However, these same parents also appear to have the following children baptised in St Ouen:
Phle [Philippe] bapt. 15.08.1802
Ann bapt. 1.12.1805
Frcs [Francis] bapt. 4.1.1807
Anne bapt. 27.05.1809
Maria bapt. 14.02.1813
Jeanne bapt 11.03.1815
Rachel bapt. 16.03.1817
Wm [William] bapt. 21.02.1819
Eliz [abeth] bapt. 5.08.1821
I trust you already have the 1841 census.
I have also found a Jacques Le Brocq in 1851, St Ouen, - but aged 68 years, so too old.
I looked for a burial for Jacques up to 1842 in St Ouen, and in St Helier deaths index 1842 - 1851 but no success.
Mike