Last weekend’s call to Mr Cameron is thought to have been warm and polite but underlines Theresa May’s political weakness Lewis Whyld/PA

Theresa May called David Cameron to beg for his support over the DUP-Tory deal last weekend, causing embarrassment on both sides.

The prime minister is understood to have made the approach last Sunday, a day before the agreement was formally sealed. It was the first time they had spoken properly in several months.

The supportive tweet came after Mrs May asked for help over the DUP deal

It came after an unsuccessful Tory election operation that disowned large parts of the Cameron legacy. The campaign was conducted by Mrs May’s staff with barely disguised hostility for their predecessors and ultimately cost the party its majority. Mr Cameron has previously told friends he does not understand Mrs May, despite working with her for more than a decade.

Last weekend’s call is thought to have been warm and polite but underlines…