According to Thurlow, under Tyndall the NF represented "an attempt to portray the essentials of Nazi ideology in more rational language and seemingly reasonable arguments", functioning as an attempt to "convert racial populists" angry about immigration "into fascists". Capitalising on anger surrounding the arrival of Ugandan Asian migrants in the country in 1972, Tyndall oversaw the NF during the period of its largest growth. Membership of the party doubled between October 1972 and June 1973, possibly reaching as high as 17,500.