The first half a dozen I entered didn't go in - how can Palmer's Green, Hanwell, Harrow-on-the-Hill not be an overground station? You must have left out half the overground lines.
Palmers Green is on the Great northern, Hanwell is on the TFL rail & Great Western Railway, Harrow-on-the-Hill is on the Chiltern Railways and London Underground Metropolitan Line. None of them are on the London Overground.
2. You misspelled Canonbury.
3. You missed out 3 lines (Cheshunt-Enfield, Chingford, Romford)
4. accept Highbury & Islington for highbury and islington.
5. You forgot Battersea Park (services in early morning from H & I)