Complex sentence: Whereas Scott's work had clearly been in sympathy with the existing building, Grimthorpe's plans reflected the Victorian ideal--indeed he spent considerable time dismissing and criticising the work of Scott and the efforts of his son.
Split into simpler sentences: Whereas Scott's work had clearly been in sympathy with the existing building, Grimthorpe's plans reflected the Victorian ideal. Indeed, he spent considerable time dismissing and criticising the work of Scott and the efforts of his son.