British tanks were NOT superior to German tanks, in fact, the British had quite possibly the worst tanks of any major nation in the war.
Char B's were quite good tanks, with more firepower and protection than PzKpfW III's (the German panzers at the time), but, they had 3 essential faults.
(1) They were employed improperly, attached to infantry regiments in small numbers rather than formed into independant armoured units.
(2) They were not as mobile as the panzers. In tank battles of the time, mobility was a lot more important than protection or firepower, since mobility allowed better flanking which resulted in side or rear hits, or the ability to engage at very close range, at which point advantages in protection and firepower are largely negated and tanks become more or less equal.
(3) A major problem with the Char B design was that it had only a 3 man crew rather than 4. This led to a lot of problems under heavy engagement and reduced the tank's initiative in certain situations, particularly when facing combined attacks from armour and infantry.