The prime minister marked the anniversary with a speech in which she appealed to the main Labour opposition party to help implement her policies, a month after losing her majority in a general election.

Amid rumours of plans to oust her, May accepted that "the reality I now face as prime minister is rather different" than it was before the June 8 election.

May took over last year after her predecessor David Cameron resigned in the wake of a shock referendum result that saw Britain vote to leave the European Union.

The austere vicar's daughter was seen as a safe pair of hands who could heal a Conservative Party that emerged bitterly divided from the referendum.

But her government has been forced into a series of embarrassing U-turns and her gamble of holding an early election backfired spectacularly.

Key parts of her Brexit plan are now also under fire from critics within her own party who want a more moderate approach and whose voices are suddenly influential because of the election result.