Possible Cetti’s Warbler?

Hoping to get some opinions please!  
Been on a walk today and spotted this bird. We actually thought it was a wren initially, but looking at these photos, I thought it could possibly be a Cetti’s Warbler. 
It only stayed around for a few moments, then disappeared into the undergrowth. Seen in an inner city nature reserve in Stoke-on-Trent, Staffordshire, and was seen relatively close to a brook.

Thank you,

Kerry