Chilli Plants - New buds going yellow and dying!

Stevie wrote:
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There will be no insect pollinators in your conservatory but it isn't clear if this is important, however it may be a problem with other fruiting plants that require pollinators.
MacGregor who is usually the expert I go to on pollination is uncertain:
<quote> The pollination requirements for maximum production of the different cultivars of pepper is not clear. Jones and Rosa (1928*) stated that "Self-pollination takes place, in general, but there appears to be a considerable percentage of cross-pollination also, for many hybrids have been noticed as a result of growing different varieties near each other." Hawthorn and Pollard (1954*) implied the same thing. Cobley (1956*) concluded that both self and cross-pollination occurred for which he gave credit to ants. Dempsey (1961) found no difference in set of open flowers and those caged in special cone cages. Cochran (1936) stated that flowers emasculated and bagged set fruit as well as open-pollinated flowers, which without qualifications is difficult to accept. Later, however, he (1938) conceded that cross-pollination takes place more frequently than is generally supposed. Martin and Crawford (1951), Peterson (1958), and Shifriss and Frankel (1969) reported male sterility in peppers, which is accentuated by higher temperatures (Bashir 1953). Hirose (1959, 1962) reported that high temperatures 13 to 17 days before anthesis causes pollen abortion and the deterioration of pollination efficiency. Odland and Porter (1941) found that none of the varieties tested were entirely self- fertilized and concluded that there is more cross-pollination than is generally realized. Erwin (1932) measured the effect of pollination on set of fruit. He found that only 46 percent of self-pollinated flowers set compared to 71 percent that were left to open pollination by bees. Nagarathnam and Rajamani (1963) obtained only 6 to 11 percent set of the flowers present. Angeli (1957) reported that hybrid pepper ripens earlier, produces more, and is more disease resistant than the parents. He also stated that production of seed by open pollination was unsatisfactory because of the lack of insect pollinators. Cochran (1932) reported that high nitrogen and low soil moisture at flowering time increase set, but high nitrogen and high moisture increase production. The period of receptivity of the stigma has not been too well determined, but apparently it functions only the first day the flower opens. Smith (1932) noted that few tomato flowers with elongated styles develop normally and set fruit. As previously mentioned, the pepper style varies in length also. Quite conceivably, in the absence of pollinating insects, the long style would prevent pollen from the anthers reaching the stigma, and fruit setting would be prevented or reduced. Markus (1965) noted that crossing occurred primarily between 7 and 11 a.m. The evidence indicates that pepper flowers do not always release their pollen, or if it is released, it may not come in contact with the stigma. Under such conditions, the transfer of pollen between flowers by an outside agency is essential. Pollinators: file:///E|/Jason/book/chap6/pepper.html (3 of 6) [1/21/2009 3:46:48 PM] Chapter 6: Common Vegetables for Seed and Fruit Boswell (1937) stated that peppers are cross-fertilized to a considerable extent but did not state what agencies were responsible. Although ants are frequently mentioned in relation to pollination of peppers, their type of activity, the lack of a dense coat of hairs on their body, and their limited number in relation to the blossoms present in a commercial planting, would indicate that they have received more credit as pollinators of pepper than they deserve. Honey bees and other bees visit the flowers of pepper on warm bright days (Hawthorn and Pollard 1954*) or during dry periods (Erwin 1931, 1932; Markus 1964; Odland and Porter 1941; Pammel and King p. 605, 1930*). Other members of the family Solanaceae are noted for their low attractiveness to bees, for example, potatoes, tobacco, eggplants, and petunias, although when other sources of nectar or pollen are scarce these plants may be visited. This would appear to apply to peppers also. Wind, rain, and other insects appear to be of little or no value in the pollination of peppers. Pollination Recommendations and Practices: None. <unquote>
Make of that what you will, it seems contradictory to me but it leaves open the possibility that you are getting incomplete pollination.
If your watering via the bottom results in the soil getting damp up to the top and they are not waterlogged it will be fine. Dig down from the top an hour after watering and see where the soil is damp, if it isn't damp 3cm from the top you had better change to top watering. Make sure the pots drain well.
How many hours a day of sun do they get?
At this point i think that the problem is the temperature. I am assuming you are using Celsius not Fahrenheit otherwise forget chillis! If you have a max/min thermometer put it in the conservatory and note the temperatures daily. I am guessing it gets too cold at night. Peppers like it warm.
David