Try www.woolies-trim.co.uk -- match to your existing, think they do the Furflex too. Sold by the yard
Window moulding bottom pieces generally called "scraper mouldings" if you have to 'phone to ask
Gone: '59 Mark I, '56 Mark VIIM, '59 Mark IX, '01 XJ8 Sovereign 4L LWB, '01 XJ8 Sport 3.2L, '01 XJ8 Exec 3.2L
Current: '03 Strange Rover L322
In trim shop for total refurb: '73 Owen Sedanca 4.2L
Stalled in storage '61 Mark IX with 4.2L
Sadly, my experience of modern front/rear window seals is that they don't compare well with the Jaguar originals and make screen fitting and sealing difficult. After using two repro front seals, I was forced to re-use my original somewhat elderly front screen seal to achieve a decent fit/seal. Also, on a series 1, ensure you get the correct seal for the width of chrome window trim fitted. There are two seals to suit the two different trim widths for early (up to 1G 4158, 1G 51906, 1L 5576, 1L 52957) and later cars. Mike.
2014 XK Dynamic R convertible; 1977 Daimler Double Six Coupe; XE S
One of the few useful tips from Wheeler Dealers: make a slit in the old seal, and insert some foam, and glue/tape up the slit. Only works if they're not perished, of course.
<edit>Drat, misinterpreted the question as Door Seals. Of course, you can't stuff foam in a window seal.</edit>
1981 XJ6 Series III basket case
1991 XJS V12 "facelift"
2008 XJ TDVi