Charles Ellson wrote:

Get on your bike and try the road route. I can't find anything about a
closure but I suspect a better question would be something on the
lines of "Why don't they run some trains via Primrose Hill to
compensate?" (assuming the NLL isn't closed east of Camden Road).

Exactly like they are doing, you mean?

http://snurl.com/3hvuq is the relevant page on the TfL site, which has
a PDF version of the closure leaflet thereon.

Revised train timetables can be found at http://snurl.com/3hvuz.

The basic plan is as follows:

1st September to 16th November : No service Gospel Oak - Willesden Junction

1st September to 28th September : No service Gospel Oak - Barking

22nd September to 28th September : No service Gospel Oak - Camden Road

Train Service Summary:

No service South Hampstead - Euston on Mondays to Saturdays from 1st
September to 15th November.

Up to 3 tph Watford Junction - Stratford via Primrose Hill, calling at
all intermediate stations, on Mondays to Saturdays from 1st September to
15th November. Also 2 tph Gospel Oak - Stratford (Camden Road -
Stratford from 22nd to 28th September).

On Sundays, from 7th September to 16th November, 2 tph Watford Junction
- Euston, and 2 tph Willesden Junction (Low Level) - Stratford via
Primrose Hill. Also 2 tph Gospel Oak - Kentish Town West - Camden Road -
Highbury & Islington (except 28th September).

Normal service Richmond - Willesden Junction and Willesden Junction -
Clapham Junction.

Replacement bus services:

Service A (from 1st September to 16th November): Gospel Oak - Hampstead
Heath - South Hampstead - West Hampstead - Brondesbury - Brondesbury
Park - Queen's Park - Kensal Rise

NB: This may be a typo, as the accompanying map suggests buses will run
through to Willesden Junction.

Service B (from 1st September to 28th September): Gospel Oak - Upper
Holloway - Crouch Hill - Harringay Green Lanes - South Tottenham - Seven
Sisters - Blackhorse Road

Service C (from 1st September to 28th September): Blackhorse Road -
Walthamstow Central - Leyton Midland Road - Leytonstone High Road -
Wanstead Park - Woodgrange Park - Barking

Service D (from 22nd to 28th September): Gospel Oak - Kentish Town West
- Camden Road

Valid tickets will be accepted on "some" local bus routes (unspecified
which ones though!) and the following train services:

London Midland : Euston - Watford Junction
First Capital Connect (Thameslink route) : West Hampstead Thameslink -
Kentish Town
c2c : Barking - West Ham

Cheers,

Barry