Rangers retail partners Castore are set to produce kits for Scottish Premiership rivals Hearts after striking a new deal with Umbro. The controversial retailers have announced a new deal with the legendary brand which will allow Castore to market Umbro in the UK, Germany, Austria, Switzerland, Belgium, Netherlands, and Denmark. This comes after fresh £145m investment in November and marks something of a new era for Castore, who have aims to become a “multi-brand business”. The new Umbro deal comes with Castore disrupting the global sporting influence of gargantuan retailers Nike and Adidas, th…