Rover Streetwise intermittent no tickover on starter motor

Once started drives fine no issues:

Intermittent issue when starting car no tick over on starter motor (sometimes tries to turn and starter sounds out of alignment with grinding noise but then cuts out won't respond after) then no response,

Under bonnet when key turned to position III the relays operate in fuse box and a whirring noise after but nothing from starter motor.

If left for number of hours will startup with no grinding sound occasionally seems very random but more frequent this past few days.

A Colleague of mine has just had a look under suspecting it maybe a faulty connection to the starter motor corrosion on spade etc from winter weather or bumpy rides loose connection. He secured connection and Engine whether coincedence has started up fine with no dodgy sounds. If this issue persists what else is it worth having checked if this turns out to be a coincedence. Thanks in Advance. CG