The phrase "and formerly when" is not correct and does not convey a clear meaning in written English.
It seems to attempt to refer to a past time or condition, but the structure is awkward and unclear.
Example: "The project was successful, and formerly when we had similar challenges, we approached them differently."
Alternatives: "and in the past when" or "and previously when".
Formerly, when government functions were limited and the property tax was the sole source of local income, tax rates were determined simply by dividing the figure for estimated expenditure by that for assessed valuation.
General practitioners are spread more evenly over the country than formerly, when there were many in the richer areas and few in the industrial towns.
(In 1886, though, when his stories first began attracting notice, he reported a similar feeling of invasion to his friend Viktor Bilibin: "Formerly, when I didn't know that they read my tales and passed judgment on them, I wrote serenely, just the way I eat pancakes; now, I'm afraid when I write").
Formerly, when the economy was based primarily on fishing, each group claimed a distinctive culture and political autonomy.
Formerly, when ropiness occurred, bakers acidified doughs with vinegar as a protective measure, but this type of spoilage is rare in bread from modern bakeries.
Formerly, when the church was not used for dining, you ate in a smaller room in the Mission House and had to be finished in seven and a half minutes.
Formerly, when I could seldom spare money, I kept catalogues as much as possible out of sight; now I savour them page by page, and make a pleasant virtue of the discretion I must needs impose upon myself.
Formerly, when a Privy Counsellor rose to make a speech in the House of Commons at the same time as another member, the Speaker would first recognise the Privy Counsellor.
Formerly, when patients needed primary care outside office hours, the probability of being seen by their own or a local GP with whom they were familiar, was higher.
Formerly, when the breed was more numerous, its distribution extended north into the department of Aude, but the survey indicated that the breed there has been either absorbed or displaced by Lacaune.
