I’m not sure how up to date this information is but it was correct a couple of years ago.
John McMaster, formerly of Lewmar Scotland, branched off to form his own Lewmar spares company, called SL Spares. John purchased the SL Toilet business from Lewmar, covering the 391 Kentigern, 396 Standard and the 400/401, for spares and servicing. He was also be able to supply discounted windlass stock for the SL Seawolf, SL Sealion and SL Francis.
If you search the posts for December 2004, think it was headed cleaning rubber toilet parts, I am sure that I posted the address of a Company that holds Service Kits, but very expensive.
Simpson-Lawrence's stock of parts were bought up by Yacht Parts Plymouth (at Queen Anne's Battery marina. i got a replacement pump from them a couple of years ago.