Paul Redpath was last seen on September 1 in Workington, Cumbria, but may have travelled to the Capital due to his links with Scotland.
The 40-year-old was released early from jail after serving 179 days of a 16 month sentence under the automatic early release scheme.
A former chef, Redpath was first jailed in Northern Ireland in 2006 for abusing two teens.
He has since absconded six times despite the fact that he should have been closely monitored according to reports.
Mr Redpath is described as 6ft 4in tall and is slim with a grey moustache and beard. His hair is in a ponytail.
Anyone who has seen him has been asked to call 101 and ask for Cumbria Police.