379. 'Aggravation by service'.

The issue of aggravation only arises if the issue of attributability has been decided against the claimant1. No question of aggravation arises unless the condition existed before service or unless it arose during service without service being a cause of its onset2. This may happen, however, even where the disease was not recognised before the person joined the forces3. It is for the Secretary of State to establish that the condition arose before service, which may be difficult in diseases which are insidious in onset or exist before symptoms appear or lie dormant, but the actual disease must be