Hi
@badmintonflyinginsect I think the effects you mentioned are natural consequences of increased government borrowing. Increased borrowing firstly means an increase in demand for government bonds, which, in the absence of a proportionate increase in supply, results in a decrease in bond price, which leads to an increase in yields. Secondly, increased government borrowing comes with increased defaulting risk, which bond markets price by demanding higher yields as compensation.
On the general interest rate side, an increase of government borrowing can firstly lead to increased government spending, which can be inflationary and thus lead to central banks increasing interest rates. Secondly, rising government borrowing can theoretically have a "crowding out" effect: because of its size, it can absorb a large portion of the economy's lending capacity, potentially leading to higher interest rates across the entire economy, including for private sector businesses and individuals.
Nonetheless, while these consequences follow from an economic theory perspective if you look at this point of fiscal policy in isolation, I do not actullay expect them to end up materialising in practice (at least in a very strong and impactful sense). Firstly, on the yields side: modern governments rise and fall on the reaction of bond markets, as seen with Liz Truss' disastrous mini budget, and this Labour government is very unlikely to take the risk of a similar situation occurring. If there is any wind of a negative outlook as to the country's defaulting risk, this will likely result in further tax rises. Secondly, on the interest rate side, I would not expect this crowding out effect to occur, simply because the UK government has access to immense pools of international public and private capital; and following this post-Covid inflationary period, I think government spending is something that will be a lot more tightly controlled.