Any contradiction or dispute ultimately stems from interests. The British Government's interference indeed caused trouble for the negotiations.
However, this did not change the British's nature of talking big without substantial action. They verbally supported the Spanish Government, but when it came to practical measures, they were full of excuses and delays.
This was an inevitable result, and while moral support posed no issue, providing actual financial support to Spain would be costly in terms of human lives.
Since the Russians set the precedent of defaulting, Britannia has not been spared from encountering breaches in debt in the recent years.
Although subsequent debtors did not blatantly default like the Russians, many genuinely lacked funds, leaving London's financial institutions helpless.