** Polymer maker Synthomer's SYNTS.L shares jump 72.2% to 31p; top gainer across London indices
** Co says its refinancing talks with lenders making progress
** Says passing on increases in raw material costs and energy costs from the Iran war to customers
** Co says overall trading since the start of 2026 is in line with co's expectations
** Co says joint venture manufacturing operation and sales office in Middle East are both currently operational
** YTD, stock down about 71.56%
($1 = 0.7539 pounds)
(Reporting by Rishab Shaju in Bengaluru)
(((Rishab.shaju@thomsonreuters.com ; +91 9048142177)))