Answer based on context:

The Senussi defeats in the Coastal Campaign forced the survivors over the border into Libya and to prevent a revival, the light Fords and armoured cars continued their patrols. The Aulad Ali surrendered to Peyton, having also gone hungry in the famine and public unrest in Alexandria diminished. The South African Brigade returned to Alexandria and two battalions of the Composite Brigade, a company of the Camel Corps, two guns of the Hong Kong Battery, the light armoured cars and the reconnaissance aircraft remained in Sollum, with an RFC half-flight. On 7 April, four light armoured cars and a machine-gun section of the 2/7th Middlesex left Sollum to raid an ammunition dump at Moraisa, 18 mi  to the north-west and destroyed artillery ammunition and about 120,000 rounds of small-arms ammunition; other patrols that month uncovered another 167,000 rounds. The Italian army posted two battalions at Bardia to co-operate and from 25-26 July, a raiding force from Sollum and Italian cars from Bardia, a party from the Camel Corps and an Italian yacht, Misurat attacked a party of about forty Muhafizia at Wadi Sanal in Libya, 40 mi  west of Ras el Mehl. The party was scattered and served as a warning that there was no sanctuary on either side of the border. Patrols continued for the year and a camel convoy was captured near Jaghbub, a Senussi stronghold 135 mi  from Sollum; more combined Italian-British raids were made during the winter.

Who remained in Sollum?
the Composite Brigade