There are a number of manufacturers around who do reproduction tiles. One approach would be to get paint colour charts from the shops and find a sample colour that is closest to the colour of your tiles. Then you locate a tile outlet near you (or far away if none nearest are useful) and ask for their advice/comment. Talking pages (0800 600 900), the Net or even architectural salvage (see Yellow pages) people (who just may have the exact tiles lying around) might lead you to a repro source. Keep asking and you will locate a repro source, but whether the colour match is perfect remains to be seen. Personally, I very much doubt that the original 30s manufacturer will still exist (even as a component of a new firm) and it is almost certain that the original colour etc. is not in standard manufacture except just possibly as repro. As has been said, you can actually have a more or less exact match made but small numbers will likely cost quite a bit - up to you to weigh against your own priorities, etc. Again, repro sources can answer questions along that line. Best of luck.